Initial

system/Database/BasePreparedQuery.php

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+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use BadMethodCallException;
+use CodeIgniter\Events\Events;
+
+/**
+ * Base prepared query
+ */
+abstract class BasePreparedQuery implements PreparedQueryInterface
+{
+    /**
+     * The prepared statement itself.
+     *
+     * @var object|resource
+     */
+    protected $statement;
+
+    /**
+     * The error code, if any.
+     *
+     * @var int
+     */
+    protected $errorCode;
+
+    /**
+     * The error message, if any.
+     *
+     * @var string
+     */
+    protected $errorString;
+
+    /**
+     * Holds the prepared query object
+     * that is cloned during execute.
+     *
+     * @var Query
+     */
+    protected $query;
+
+    /**
+     * A reference to the db connection to use.
+     *
+     * @var BaseConnection
+     */
+    protected $db;
+
+    public function __construct(BaseConnection $db)
+    {
+        $this->db = &$db;
+    }
+
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * NOTE: This version is based on SQL code. Child classes should
+     * override this method.
+     *
+     * @return mixed
+     */
+    public function prepare(string $sql, array $options = [], string $queryClass = 'CodeIgniter\\Database\\Query')
+    {
+        // We only supports positional placeholders (?)
+        // in order to work with the execute method below, so we
+        // need to replace our named placeholders (:name)
+        $sql = preg_replace('/:[^\s,)]+/', '?', $sql);
+
+        /** @var Query $query */
+        $query = new $queryClass($this->db);
+
+        $query->setQuery($sql);
+
+        if (! empty($this->db->swapPre) && ! empty($this->db->DBPrefix)) {
+            $query->swapPrefix($this->db->DBPrefix, $this->db->swapPre);
+        }
+
+        $this->query = $query;
+
+        return $this->_prepare($query->getOriginalQuery(), $options);
+    }
+
+    /**
+     * The database-dependent portion of the prepare statement.
+     *
+     * @return mixed
+     */
+    abstract public function _prepare(string $sql, array $options = []);
+
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     *
+     * @return ResultInterface
+     */
+    public function execute(...$data)
+    {
+        // Execute the Query.
+        $startTime = microtime(true);
+
+        $this->_execute($data);
+
+        // Update our query object
+        $query = clone $this->query;
+        $query->setBinds($data);
+
+        $query->setDuration($startTime);
+
+        // Let others do something with this query
+        Events::trigger('DBQuery', $query);
+
+        // Return a result object
+        $resultClass = str_replace('PreparedQuery', 'Result', static::class);
+
+        $resultID = $this->_getResult();
+
+        return new $resultClass($this->db->connID, $resultID);
+    }
+
+    /**
+     * The database dependant version of the execute method.
+     */
+    abstract public function _execute(array $data): bool;
+
+    /**
+     * Returns the result object for the prepared query.
+     *
+     * @return mixed
+     */
+    abstract public function _getResult();
+
+    /**
+     * Explicitly closes the statement.
+     */
+    public function close()
+    {
+        if (! is_object($this->statement) || ! method_exists($this->statement, 'close')) {
+            return;
+        }
+
+        $this->statement->close();
+    }
+
+    /**
+     * Returns the SQL that has been prepared.
+     */
+    public function getQueryString(): string
+    {
+        if (! $this->query instanceof QueryInterface) {
+            throw new BadMethodCallException('Cannot call getQueryString on a prepared query until after the query has been prepared.');
+        }
+
+        return $this->query->getQuery();
+    }
+
+    /**
+     * A helper to determine if any error exists.
+     */
+    public function hasError(): bool
+    {
+        return ! empty($this->errorString);
+    }
+
+    /**
+     * Returns the error code created while executing this statement.
+     */
+    public function getErrorCode(): int
+    {
+        return $this->errorCode;
+    }
+
+    /**
+     * Returns the error message created while executing this statement.
+     */
+    public function getErrorMessage(): string
+    {
+        return $this->errorString;
+    }
+}

system/Database/BaseResult.php

@@ -0,0 +1,512 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\Entity\Entity;
+
+/**
+ * Class BaseResult
+ */
+abstract class BaseResult implements ResultInterface
+{
+    /**
+     * Connection ID
+     *
+     * @var object|resource
+     */
+    public $connID;
+
+    /**
+     * Result ID
+     *
+     * @var false|object|resource
+     */
+    public $resultID;
+
+    /**
+     * Result Array
+     *
+     * @var array[]
+     */
+    public $resultArray = [];
+
+    /**
+     * Result Object
+     *
+     * @var object[]
+     */
+    public $resultObject = [];
+
+    /**
+     * Custom Result Object
+     *
+     * @var array
+     */
+    public $customResultObject = [];
+
+    /**
+     * Current Row index
+     *
+     * @var int
+     */
+    public $currentRow = 0;
+
+    /**
+     * The number of records in the query result
+     *
+     * @var int|null
+     */
+    protected $numRows;
+
+    /**
+     * Row data
+     *
+     * @var array|null
+     */
+    public $rowData;
+
+    /**
+     * Constructor
+     *
+     * @param object|resource $connID
+     * @param object|resource $resultID
+     */
+    public function __construct(&$connID, &$resultID)
+    {
+        $this->connID   = $connID;
+        $this->resultID = $resultID;
+    }
+
+    /**
+     * Retrieve the results of the query. Typically an array of
+     * individual data rows, which can be either an 'array', an
+     * 'object', or a custom class name.
+     *
+     * @param string $type The row type. Either 'array', 'object', or a class name to use
+     */
+    public function getResult(string $type = 'object'): array
+    {
+        if ($type === 'array') {
+            return $this->getResultArray();
+        }
+
+        if ($type === 'object') {
+            return $this->getResultObject();
+        }
+
+        return $this->getCustomResultObject($type);
+    }
+
+    /**
+     * Returns the results as an array of custom objects.
+     *
+     * @return mixed
+     */
+    public function getCustomResultObject(string $className)
+    {
+        if (isset($this->customResultObject[$className])) {
+            return $this->customResultObject[$className];
+        }
+
+        if (is_bool($this->resultID) || ! $this->resultID) {
+            return [];
+        }
+
+        // Don't fetch the result set again if we already have it
+        $_data = null;
+        if (($c = count($this->resultArray)) > 0) {
+            $_data = 'resultArray';
+        } elseif (($c = count($this->resultObject)) > 0) {
+            $_data = 'resultObject';
+        }
+
+        if ($_data !== null) {
+            for ($i = 0; $i < $c; $i++) {
+                $this->customResultObject[$className][$i] = new $className();
+
+                foreach ($this->{$_data}[$i] as $key => $value) {
+                    $this->customResultObject[$className][$i]->{$key} = $value;
+                }
+            }
+
+            return $this->customResultObject[$className];
+        }
+
+        if ($this->rowData !== null) {
+            $this->dataSeek();
+        }
+        $this->customResultObject[$className] = [];
+
+        while ($row = $this->fetchObject($className)) {
+            if (! is_subclass_of($row, Entity::class) && method_exists($row, 'syncOriginal')) {
+                $row->syncOriginal();
+            }
+
+            $this->customResultObject[$className][] = $row;
+        }
+
+        return $this->customResultObject[$className];
+    }
+
+    /**
+     * Returns the results as an array of arrays.
+     *
+     * If no results, an empty array is returned.
+     */
+    public function getResultArray(): array
+    {
+        if (! empty($this->resultArray)) {
+            return $this->resultArray;
+        }
+
+        // In the event that query caching is on, the result_id variable
+        // will not be a valid resource so we'll simply return an empty
+        // array.
+        if (is_bool($this->resultID) || ! $this->resultID) {
+            return [];
+        }
+
+        if ($this->resultObject) {
+            foreach ($this->resultObject as $row) {
+                $this->resultArray[] = (array) $row;
+            }
+
+            return $this->resultArray;
+        }
+
+        if ($this->rowData !== null) {
+            $this->dataSeek();
+        }
+
+        while ($row = $this->fetchAssoc()) {
+            $this->resultArray[] = $row;
+        }
+
+        return $this->resultArray;
+    }
+
+    /**
+     * Returns the results as an array of objects.
+     *
+     * If no results, an empty array is returned.
+     */
+    public function getResultObject(): array
+    {
+        if (! empty($this->resultObject)) {
+            return $this->resultObject;
+        }
+
+        // In the event that query caching is on, the result_id variable
+        // will not be a valid resource so we'll simply return an empty
+        // array.
+        if (is_bool($this->resultID) || ! $this->resultID) {
+            return [];
+        }
+
+        if ($this->resultArray) {
+            foreach ($this->resultArray as $row) {
+                $this->resultObject[] = (object) $row;
+            }
+
+            return $this->resultObject;
+        }
+
+        if ($this->rowData !== null) {
+            $this->dataSeek();
+        }
+
+        while ($row = $this->fetchObject()) {
+            if (! is_subclass_of($row, Entity::class) && method_exists($row, 'syncOriginal')) {
+                $row->syncOriginal();
+            }
+
+            $this->resultObject[] = $row;
+        }
+
+        return $this->resultObject;
+    }
+
+    /**
+     * Wrapper object to return a row as either an array, an object, or
+     * a custom class.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @param mixed  $n    The index of the results to return
+     * @param string $type The type of result object. 'array', 'object' or class name.
+     *
+     * @return mixed
+     */
+    public function getRow($n = 0, string $type = 'object')
+    {
+        if (! is_numeric($n)) {
+            // We cache the row data for subsequent uses
+            if (! is_array($this->rowData)) {
+                $this->rowData = $this->getRowArray();
+            }
+
+            // array_key_exists() instead of isset() to allow for NULL values
+            if (empty($this->rowData) || ! array_key_exists($n, $this->rowData)) {
+                return null;
+            }
+
+            return $this->rowData[$n];
+        }
+
+        if ($type === 'object') {
+            return $this->getRowObject($n);
+        }
+
+        if ($type === 'array') {
+            return $this->getRowArray($n);
+        }
+
+        return $this->getCustomRowObject($n, $type);
+    }
+
+    /**
+     * Returns a row as a custom class instance.
+     *
+     * If row doesn't exists, returns null.
+     *
+     * @return mixed
+     */
+    public function getCustomRowObject(int $n, string $className)
+    {
+        if (! isset($this->customResultObject[$className])) {
+            $this->getCustomResultObject($className);
+        }
+
+        if (empty($this->customResultObject[$className])) {
+            return null;
+        }
+
+        if ($n !== $this->currentRow && isset($this->customResultObject[$className][$n])) {
+            $this->currentRow = $n;
+        }
+
+        return $this->customResultObject[$className][$this->currentRow];
+    }
+
+    /**
+     * Returns a single row from the results as an array.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @return mixed
+     */
+    public function getRowArray(int $n = 0)
+    {
+        $result = $this->getResultArray();
+        if (empty($result)) {
+            return null;
+        }
+
+        if ($n !== $this->currentRow && isset($result[$n])) {
+            $this->currentRow = $n;
+        }
+
+        return $result[$this->currentRow];
+    }
+
+    /**
+     * Returns a single row from the results as an object.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @return mixed
+     */
+    public function getRowObject(int $n = 0)
+    {
+        $result = $this->getResultObject();
+        if (empty($result)) {
+            return null;
+        }
+
+        if ($n !== $this->customResultObject && isset($result[$n])) {
+            $this->currentRow = $n;
+        }
+
+        return $result[$this->currentRow];
+    }
+
+    /**
+     * Assigns an item into a particular column slot.
+     *
+     * @param mixed $key
+     * @param mixed $value
+     *
+     * @return mixed
+     */
+    public function setRow($key, $value = null)
+    {
+        // We cache the row data for subsequent uses
+        if (! is_array($this->rowData)) {
+            $this->rowData = $this->getRowArray();
+        }
+
+        if (is_array($key)) {
+            foreach ($key as $k => $v) {
+                $this->rowData[$k] = $v;
+            }
+
+            return;
+        }
+
+        if ($key !== '' && $value !== null) {
+            $this->rowData[$key] = $value;
+        }
+    }
+
+    /**
+     * Returns the "first" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getFirstRow(string $type = 'object')
+    {
+        $result = $this->getResult($type);
+
+        return (empty($result)) ? null : $result[0];
+    }
+
+    /**
+     * Returns the "last" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getLastRow(string $type = 'object')
+    {
+        $result = $this->getResult($type);
+
+        return (empty($result)) ? null : $result[count($result) - 1];
+    }
+
+    /**
+     * Returns the "next" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getNextRow(string $type = 'object')
+    {
+        $result = $this->getResult($type);
+        if (empty($result)) {
+            return null;
+        }
+
+        return isset($result[$this->currentRow + 1]) ? $result[++$this->currentRow] : null;
+    }
+
+    /**
+     * Returns the "previous" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getPreviousRow(string $type = 'object')
+    {
+        $result = $this->getResult($type);
+        if (empty($result)) {
+            return null;
+        }
+
+        if (isset($result[$this->currentRow - 1])) {
+            $this->currentRow--;
+        }
+
+        return $result[$this->currentRow];
+    }
+
+    /**
+     * Returns an unbuffered row and move the pointer to the next row.
+     *
+     * @return mixed
+     */
+    public function getUnbufferedRow(string $type = 'object')
+    {
+        if ($type === 'array') {
+            return $this->fetchAssoc();
+        }
+
+        if ($type === 'object') {
+            return $this->fetchObject();
+        }
+
+        return $this->fetchObject($type);
+    }
+
+    /**
+     * Number of rows in the result set; checks for previous count, falls
+     * back on counting resultArray or resultObject, finally fetching resultArray
+     * if nothing was previously fetched
+     */
+    public function getNumRows(): int
+    {
+        if (is_int($this->numRows)) {
+            return $this->numRows;
+        }
+        if ($this->resultArray !== []) {
+            return $this->numRows = count($this->resultArray);
+        }
+        if ($this->resultObject !== []) {
+            return $this->numRows = count($this->resultObject);
+        }
+
+        return $this->numRows = count($this->getResultArray());
+    }
+
+    /**
+     * Gets the number of fields in the result set.
+     */
+    abstract public function getFieldCount(): int;
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    abstract public function getFieldNames(): array;
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    abstract public function getFieldData(): array;
+
+    /**
+     * Frees the current result.
+     */
+    abstract public function freeResult();
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @return mixed
+     */
+    abstract public function dataSeek(int $n = 0);
+
+    /**
+     * Returns the result set as an array.
+     *
+     * Overridden by driver classes.
+     *
+     * @return mixed
+     */
+    abstract protected function fetchAssoc();
+
+    /**
+     * Returns the result set as an object.
+     *
+     * Overridden by child classes.
+     *
+     * @return object
+     */
+    abstract protected function fetchObject(string $className = 'stdClass');
+}

system/Database/BaseUtils.php

@@ -0,0 +1,321 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Class BaseUtils
+ */
+abstract class BaseUtils
+{
+    /**
+     * Database object
+     *
+     * @var object
+     */
+    protected $db;
+
+    /**
+     * List databases statement
+     *
+     * @var bool|string
+     */
+    protected $listDatabases = false;
+
+    /**
+     * OPTIMIZE TABLE statement
+     *
+     * @var bool|string
+     */
+    protected $optimizeTable = false;
+
+    /**
+     * REPAIR TABLE statement
+     *
+     * @var bool|string
+     */
+    protected $repairTable = false;
+
+    /**
+     * Class constructor
+     */
+    public function __construct(ConnectionInterface &$db)
+    {
+        $this->db = &$db;
+    }
+
+    /**
+     * List databases
+     *
+     * @throws DatabaseException
+     *
+     * @return array|bool
+     */
+    public function listDatabases()
+    {
+        // Is there a cached result?
+        if (isset($this->db->dataCache['db_names'])) {
+            return $this->db->dataCache['db_names'];
+        }
+
+        if ($this->listDatabases === false) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unsupported feature of the database platform you are using.');
+            }
+
+            return false;
+        }
+
+        $this->db->dataCache['db_names'] = [];
+
+        $query = $this->db->query($this->listDatabases);
+        if ($query === false) {
+            return $this->db->dataCache['db_names'];
+        }
+
+        for ($i = 0, $query = $query->getResultArray(), $c = count($query); $i < $c; $i++) {
+            $this->db->dataCache['db_names'][] = current($query[$i]);
+        }
+
+        return $this->db->dataCache['db_names'];
+    }
+
+    /**
+     * Determine if a particular database exists
+     */
+    public function databaseExists(string $databaseName): bool
+    {
+        return in_array($databaseName, $this->listDatabases(), true);
+    }
+
+    /**
+     * Optimize Table
+     *
+     * @throws DatabaseException
+     *
+     * @return bool
+     */
+    public function optimizeTable(string $tableName)
+    {
+        if ($this->optimizeTable === false) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unsupported feature of the database platform you are using.');
+            }
+
+            return false;
+        }
+
+        $query = $this->db->query(sprintf($this->optimizeTable, $this->db->escapeIdentifiers($tableName)));
+
+        return $query !== false;
+    }
+
+    /**
+     * Optimize Database
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function optimizeDatabase()
+    {
+        if ($this->optimizeTable === false) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unsupported feature of the database platform you are using.');
+            }
+
+            return false;
+        }
+
+        $result = [];
+
+        foreach ($this->db->listTables() as $tableName) {
+            $res = $this->db->query(sprintf($this->optimizeTable, $this->db->escapeIdentifiers($tableName)));
+            if (is_bool($res)) {
+                return $res;
+            }
+
+            // Build the result array...
+
+            $res = $res->getResultArray();
+
+            // Postgre & SQLite3 returns empty array
+            if (empty($res)) {
+                $key = $tableName;
+            } else {
+                $res  = current($res);
+                $key  = str_replace($this->db->database . '.', '', current($res));
+                $keys = array_keys($res);
+                unset($res[$keys[0]]);
+            }
+
+            $result[$key] = $res;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Repair Table
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function repairTable(string $tableName)
+    {
+        if ($this->repairTable === false) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unsupported feature of the database platform you are using.');
+            }
+
+            return false;
+        }
+
+        $query = $this->db->query(sprintf($this->repairTable, $this->db->escapeIdentifiers($tableName)));
+        if (is_bool($query)) {
+            return $query;
+        }
+
+        $query = $query->getResultArray();
+
+        return current($query);
+    }
+
+    /**
+     * Generate CSV from a query result object
+     *
+     * @return string
+     */
+    public function getCSVFromResult(ResultInterface $query, string $delim = ',', string $newline = "\n", string $enclosure = '"')
+    {
+        $out = '';
+
+        foreach ($query->getFieldNames() as $name) {
+            $out .= $enclosure . str_replace($enclosure, $enclosure . $enclosure, $name) . $enclosure . $delim;
+        }
+
+        $out = substr($out, 0, -strlen($delim)) . $newline;
+
+        // Next blast through the result array and build out the rows
+        while ($row = $query->getUnbufferedRow('array')) {
+            $line = [];
+
+            foreach ($row as $item) {
+                $line[] = $enclosure . str_replace($enclosure, $enclosure . $enclosure, $item ?? '') . $enclosure;
+            }
+
+            $out .= implode($delim, $line) . $newline;
+        }
+
+        return $out;
+    }
+
+    /**
+     * Generate XML data from a query result object
+     */
+    public function getXMLFromResult(ResultInterface $query, array $params = []): string
+    {
+        foreach (['root' => 'root', 'element' => 'element', 'newline' => "\n", 'tab' => "\t"] as $key => $val) {
+            if (! isset($params[$key])) {
+                $params[$key] = $val;
+            }
+        }
+
+        $root    = $params['root'];
+        $newline = $params['newline'];
+        $tab     = $params['tab'];
+        $element = $params['element'];
+
+        helper('xml');
+        $xml = '<' . $root . '>' . $newline;
+
+        while ($row = $query->getUnbufferedRow()) {
+            $xml .= $tab . '<' . $element . '>' . $newline;
+
+            foreach ($row as $key => $val) {
+                $val = (! empty($val)) ? xml_convert($val) : '';
+
+                $xml .= $tab . $tab . '<' . $key . '>' . $val . '</' . $key . '>' . $newline;
+            }
+
+            $xml .= $tab . '</' . $element . '>' . $newline;
+        }
+
+        return $xml . '</' . $root . '>' . $newline;
+    }
+
+    /**
+     * Database Backup
+     *
+     * @param array|string $params
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function backup($params = [])
+    {
+        if (is_string($params)) {
+            $params = ['tables' => $params];
+        }
+
+        $prefs = [
+            'tables'             => [],
+            'ignore'             => [],
+            'filename'           => '',
+            'format'             => 'gzip', // gzip, txt
+            'add_drop'           => true,
+            'add_insert'         => true,
+            'newline'            => "\n",
+            'foreign_key_checks' => true,
+        ];
+
+        if (! empty($params)) {
+            foreach (array_keys($prefs) as $key) {
+                if (isset($params[$key])) {
+                    $prefs[$key] = $params[$key];
+                }
+            }
+        }
+
+        if (empty($prefs['tables'])) {
+            $prefs['tables'] = $this->db->listTables();
+        }
+
+        if (! in_array($prefs['format'], ['gzip', 'txt'], true)) {
+            $prefs['format'] = 'txt';
+        }
+
+        if ($prefs['format'] === 'gzip' && ! function_exists('gzencode')) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('The file compression format you chose is not supported by your server.');
+            }
+
+            $prefs['format'] = 'txt';
+        }
+
+        if ($prefs['format'] === 'txt') {
+            return $this->_backup($prefs);
+        }
+
+        return gzencode($this->_backup($prefs));
+    }
+
+    /**
+     * Platform dependent version of the backup function.
+     *
+     * @return mixed
+     */
+    abstract public function _backup(?array $prefs = null);
+}

system/Database/Config.php

@@ -0,0 +1,145 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\Config\BaseConfig;
+use InvalidArgumentException;
+
+/**
+ * Class Config
+ */
+class Config extends BaseConfig
+{
+    /**
+     * Cache for instance of any connections that
+     * have been requested as a "shared" instance.
+     *
+     * @var array
+     */
+    protected static $instances = [];
+
+    /**
+     * The main instance used to manage all of
+     * our open database connections.
+     *
+     * @var Database|null
+     */
+    protected static $factory;
+
+    /**
+     * Creates the default
+     *
+     * @param array|string $group     The name of the connection group to use, or an array of configuration settings.
+     * @param bool         $getShared Whether to return a shared instance of the connection.
+     *
+     * @return BaseConnection
+     */
+    public static function connect($group = null, bool $getShared = true)
+    {
+        // If a DB connection is passed in, just pass it back
+        if ($group instanceof BaseConnection) {
+            return $group;
+        }
+
+        if (is_array($group)) {
+            $config = $group;
+            $group  = 'custom-' . md5(json_encode($config));
+        }
+
+        $config = $config ?? config('Database');
+
+        if (empty($group)) {
+            $group = ENVIRONMENT === 'testing' ? 'tests' : $config->defaultGroup;
+        }
+
+        if (is_string($group) && ! isset($config->{$group}) && strpos($group, 'custom-') !== 0) {
+            throw new InvalidArgumentException($group . ' is not a valid database connection group.');
+        }
+
+        if ($getShared && isset(static::$instances[$group])) {
+            return static::$instances[$group];
+        }
+
+        static::ensureFactory();
+
+        if (isset($config->{$group})) {
+            $config = $config->{$group};
+        }
+
+        $connection = static::$factory->load($config, $group);
+
+        static::$instances[$group] = &$connection;
+
+        return $connection;
+    }
+
+    /**
+     * Returns an array of all db connections currently made.
+     */
+    public static function getConnections(): array
+    {
+        return static::$instances;
+    }
+
+    /**
+     * Loads and returns an instance of the Forge for the specified
+     * database group, and loads the group if it hasn't been loaded yet.
+     *
+     * @param array|ConnectionInterface|string|null $group
+     *
+     * @return Forge
+     */
+    public static function forge($group = null)
+    {
+        $db = static::connect($group);
+
+        return static::$factory->loadForge($db);
+    }
+
+    /**
+     * Returns a new instance of the Database Utilities class.
+     *
+     * @param array|string|null $group
+     *
+     * @return BaseUtils
+     */
+    public static function utils($group = null)
+    {
+        $db = static::connect($group);
+
+        return static::$factory->loadUtils($db);
+    }
+
+    /**
+     * Returns a new instance of the Database Seeder.
+     *
+     * @return Seeder
+     */
+    public static function seeder(?string $group = null)
+    {
+        $config = config('Database');
+
+        return new Seeder($config, static::connect($group));
+    }
+
+    /**
+     * Ensures the database Connection Manager/Factory is loaded and ready to use.
+     */
+    protected static function ensureFactory()
+    {
+        if (static::$factory instanceof Database) {
+            return;
+        }
+
+        static::$factory = new Database();
+    }
+}

system/Database/ConnectionInterface.php

@@ -0,0 +1,156 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+/**
+ * Interface ConnectionInterface
+ */
+interface ConnectionInterface
+{
+    /**
+     * Initializes the database connection/settings.
+     *
+     * @return mixed
+     */
+    public function initialize();
+
+    /**
+     * Connect to the database.
+     *
+     * @return mixed
+     */
+    public function connect(bool $persistent = false);
+
+    /**
+     * Create a persistent database connection.
+     *
+     * @return mixed
+     */
+    public function persistentConnect();
+
+    /**
+     * Keep or establish the connection if no queries have been sent for
+     * a length of time exceeding the server's idle timeout.
+     *
+     * @return mixed
+     */
+    public function reconnect();
+
+    /**
+     * Returns the actual connection object. If both a 'read' and 'write'
+     * connection has been specified, you can pass either term in to
+     * get that connection. If you pass either alias in and only a single
+     * connection is present, it must return the sole connection.
+     *
+     * @return mixed
+     */
+    public function getConnection(?string $alias = null);
+
+    /**
+     * Select a specific database table to use.
+     *
+     * @return mixed
+     */
+    public function setDatabase(string $databaseName);
+
+    /**
+     * Returns the name of the current database being used.
+     */
+    public function getDatabase(): string;
+
+    /**
+     * Returns the last error encountered by this connection.
+     * Must return this format: ['code' => string|int, 'message' => string]
+     * intval(code) === 0 means "no error".
+     *
+     * @return array<string, int|string>
+     */
+    public function error(): array;
+
+    /**
+     * The name of the platform in use (MySQLi, mssql, etc)
+     */
+    public function getPlatform(): string;
+
+    /**
+     * Returns a string containing the version of the database being used.
+     */
+    public function getVersion(): string;
+
+    /**
+     * Orchestrates a query against the database. Queries must use
+     * Database\Statement objects to store the query and build it.
+     * This method works with the cache.
+     *
+     * Should automatically handle different connections for read/write
+     * queries if needed.
+     *
+     * @param mixed ...$binds
+     *
+     * @return BaseResult|bool|Query
+     */
+    public function query(string $sql, $binds = null);
+
+    /**
+     * Performs a basic query against the database. No binding or caching
+     * is performed, nor are transactions handled. Simply takes a raw
+     * query string and returns the database-specific result id.
+     *
+     * @return mixed
+     */
+    public function simpleQuery(string $sql);
+
+    /**
+     * Returns an instance of the query builder for this connection.
+     *
+     * @param array|string $tableName Table name.
+     *
+     * @return BaseBuilder Builder.
+     */
+    public function table($tableName);
+
+    /**
+     * Returns the last query's statement object.
+     *
+     * @return mixed
+     */
+    public function getLastQuery();
+
+    /**
+     * "Smart" Escaping
+     *
+     * Escapes data based on type.
+     * Sets boolean and null types.
+     *
+     * @param mixed $str
+     *
+     * @return mixed
+     */
+    public function escape($str);
+
+    /**
+     * Allows for custom calls to the database engine that are not
+     * supported through our database layer.
+     *
+     * @param array ...$params
+     *
+     * @return mixed
+     */
+    public function callFunction(string $functionName, ...$params);
+
+    /**
+     * Determines if the statement is a write-type query or not.
+     *
+     * @param string $sql
+     */
+    public function isWriteType($sql): bool;
+}

system/Database/Database.php

@@ -0,0 +1,138 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use InvalidArgumentException;
+
+/**
+ * Database Connection Factory
+ *
+ * Creates and returns an instance of the appropriate DatabaseConnection
+ */
+class Database
+{
+    /**
+     * Maintains an array of the instances of all connections that have
+     * been created.
+     *
+     * Helps to keep track of all open connections for performance
+     * monitoring, logging, etc.
+     *
+     * @var array
+     */
+    protected $connections = [];
+
+    /**
+     * Parses the connection binds and returns an instance of the driver
+     * ready to go.
+     *
+     * @throws InvalidArgumentException
+     *
+     * @return mixed
+     */
+    public function load(array $params = [], string $alias = '')
+    {
+        if ($alias === '') {
+            throw new InvalidArgumentException('You must supply the parameter: alias.');
+        }
+
+        if (! empty($params['DSN']) && strpos($params['DSN'], '://') !== false) {
+            $params = $this->parseDSN($params);
+        }
+
+        if (empty($params['DBDriver'])) {
+            throw new InvalidArgumentException('You have not selected a database type to connect to.');
+        }
+
+        $this->connections[$alias] = $this->initDriver($params['DBDriver'], 'Connection', $params);
+
+        return $this->connections[$alias];
+    }
+
+    /**
+     * Creates a Forge instance for the current database type.
+     */
+    public function loadForge(ConnectionInterface $db): object
+    {
+        if (! $db->connID) {
+            $db->initialize();
+        }
+
+        return $this->initDriver($db->DBDriver, 'Forge', $db);
+    }
+
+    /**
+     * Creates a Utils instance for the current database type.
+     */
+    public function loadUtils(ConnectionInterface $db): object
+    {
+        if (! $db->connID) {
+            $db->initialize();
+        }
+
+        return $this->initDriver($db->DBDriver, 'Utils', $db);
+    }
+
+    /**
+     * Parse universal DSN string
+     *
+     * @throws InvalidArgumentException
+     */
+    protected function parseDSN(array $params): array
+    {
+        $dsn = parse_url($params['DSN']);
+
+        if (! $dsn) {
+            throw new InvalidArgumentException('Your DSN connection string is invalid.');
+        }
+
+        $dsnParams = [
+            'DSN'      => '',
+            'DBDriver' => $dsn['scheme'],
+            'hostname' => isset($dsn['host']) ? rawurldecode($dsn['host']) : '',
+            'port'     => isset($dsn['port']) ? rawurldecode((string) $dsn['port']) : '',
+            'username' => isset($dsn['user']) ? rawurldecode($dsn['user']) : '',
+            'password' => isset($dsn['pass']) ? rawurldecode($dsn['pass']) : '',
+            'database' => isset($dsn['path']) ? rawurldecode(substr($dsn['path'], 1)) : '',
+        ];
+
+        if (! empty($dsn['query'])) {
+            parse_str($dsn['query'], $extra);
+
+            foreach ($extra as $key => $val) {
+                if (is_string($val) && in_array(strtolower($val), ['true', 'false', 'null'], true)) {
+                    $val = $val === 'null' ? null : filter_var($val, FILTER_VALIDATE_BOOLEAN);
+                }
+
+                $dsnParams[$key] = $val;
+            }
+        }
+
+        return array_merge($params, $dsnParams);
+    }
+
+    /**
+     * Initialize database driver.
+     *
+     * @param array|object $argument
+     */
+    protected function initDriver(string $driver, string $class, $argument): object
+    {
+        $class = $driver . '\\' . $class;
+
+        if (strpos($driver, '\\') === false) {
+            $class = "CodeIgniter\\Database\\{$class}";
+        }
+
+        return new $class($argument);
+    }
+}

system/Database/Exceptions/DataException.php

@@ -0,0 +1,85 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Exceptions;
+
+use CodeIgniter\Exceptions\DebugTraceableTrait;
+use RuntimeException;
+
+class DataException extends RuntimeException implements ExceptionInterface
+{
+    use DebugTraceableTrait;
+
+    /**
+     * Used by the Model's trigger() method when the callback cannot be found.
+     *
+     * @return DataException
+     */
+    public static function forInvalidMethodTriggered(string $method)
+    {
+        return new static(lang('Database.invalidEvent', [$method]));
+    }
+
+    /**
+     * Used by Model's insert/update methods when there isn't
+     * any data to actually work with.
+     *
+     * @return DataException
+     */
+    public static function forEmptyDataset(string $mode)
+    {
+        return new static(lang('Database.emptyDataset', [$mode]));
+    }
+
+    /**
+     * Used by Model's insert/update methods when there is no
+     * primary key defined and Model has option `useAutoIncrement`
+     * set to false.
+     *
+     * @return DataException
+     */
+    public static function forEmptyPrimaryKey(string $mode)
+    {
+        return new static(lang('Database.emptyPrimaryKey', [$mode]));
+    }
+
+    /**
+     * Thrown when an argument for one of the Model's methods
+     * were empty or otherwise invalid, and they could not be
+     * to work correctly for that method.
+     *
+     * @return DataException
+     */
+    public static function forInvalidArgument(string $argument)
+    {
+        return new static(lang('Database.invalidArgument', [$argument]));
+    }
+
+    public static function forInvalidAllowedFields(string $model)
+    {
+        return new static(lang('Database.invalidAllowedFields', [$model]));
+    }
+
+    public static function forTableNotFound(string $table)
+    {
+        return new static(lang('Database.tableNotFound', [$table]));
+    }
+
+    public static function forEmptyInputGiven(string $argument)
+    {
+        return new static(lang('Database.forEmptyInputGiven', [$argument]));
+    }
+
+    public static function forFindColumnHaveMultipleColumns()
+    {
+        return new static(lang('Database.forFindColumnHaveMultipleColumns'));
+    }
+}

system/Database/Exceptions/DatabaseException.php

@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Exceptions;
+
+use Error;
+
+class DatabaseException extends Error implements ExceptionInterface
+{
+    /**
+     * Exit status code
+     *
+     * @var int
+     */
+    protected $code = 8;
+}

system/Database/Exceptions/ExceptionInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Exceptions;
+
+/**
+ * Provides a domain-level interface for broad capture
+ * of all database-related exceptions.
+ *
+ * catch (\CodeIgniter\Database\Exceptions\ExceptionInterface) { ... }
+ */
+interface ExceptionInterface extends \CodeIgniter\Exceptions\ExceptionInterface
+{
+}

system/Database/Migration.php

@@ -0,0 +1,73 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use Config\Database;
+
+/**
+ * Class Migration
+ */
+abstract class Migration
+{
+    /**
+     * The name of the database group to use.
+     *
+     * @var string
+     */
+    protected $DBGroup;
+
+    /**
+     * Database Connection instance
+     *
+     * @var ConnectionInterface
+     */
+    protected $db;
+
+    /**
+     * Database Forge instance.
+     *
+     * @var Forge
+     */
+    protected $forge;
+
+    /**
+     * Constructor.
+     *
+     * @param Forge $forge
+     */
+    public function __construct(?Forge $forge = null)
+    {
+        $this->forge = $forge ?? Database::forge($this->DBGroup ?? config('Database')->defaultGroup);
+
+        $this->db = $this->forge->getConnection();
+    }
+
+    /**
+     * Returns the database group name this migration uses.
+     *
+     * @return string
+     */
+    public function getDBGroup(): ?string
+    {
+        return $this->DBGroup;
+    }
+
+    /**
+     * Perform a migration step.
+     */
+    abstract public function up();
+
+    /**
+     * Revert a migration step.
+     */
+    abstract public function down();
+}

system/Database/MigrationRunner.php

@@ -0,0 +1,867 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\CLI\CLI;
+use CodeIgniter\Events\Events;
+use CodeIgniter\Exceptions\ConfigException;
+use Config\Database;
+use Config\Migrations as MigrationsConfig;
+use Config\Services;
+use RuntimeException;
+use stdClass;
+
+/**
+ * Class MigrationRunner
+ */
+class MigrationRunner
+{
+    /**
+     * Whether or not migrations are allowed to run.
+     *
+     * @var bool
+     */
+    protected $enabled = false;
+
+    /**
+     * Name of table to store meta information
+     *
+     * @var string
+     */
+    protected $table;
+
+    /**
+     * The Namespace  where migrations can be found.
+     *
+     * @var string|null
+     */
+    protected $namespace;
+
+    /**
+     * The database Group to migrate.
+     *
+     * @var string
+     */
+    protected $group;
+
+    /**
+     * The migration name.
+     *
+     * @var string
+     */
+    protected $name;
+
+    /**
+     * The pattern used to locate migration file versions.
+     *
+     * @var string
+     */
+    protected $regex = '/^\d{4}[_-]?\d{2}[_-]?\d{2}[_-]?\d{6}_(\w+)$/';
+
+    /**
+     * The main database connection. Used to store
+     * migration information in.
+     *
+     * @var BaseConnection
+     */
+    protected $db;
+
+    /**
+     * If true, will continue instead of throwing
+     * exceptions.
+     *
+     * @var bool
+     */
+    protected $silent = false;
+
+    /**
+     * used to return messages for CLI.
+     *
+     * @var array
+     */
+    protected $cliMessages = [];
+
+    /**
+     * Tracks whether we have already ensured
+     * the table exists or not.
+     *
+     * @var bool
+     */
+    protected $tableChecked = false;
+
+    /**
+     * The full path to locate migration files.
+     *
+     * @var string
+     */
+    protected $path;
+
+    /**
+     * The database Group filter.
+     *
+     * @var string|null
+     */
+    protected $groupFilter;
+
+    /**
+     * Used to skip current migration.
+     *
+     * @var bool
+     */
+    protected $groupSkip = false;
+
+    /**
+     * Constructor.
+     *
+     * When passing in $db, you may pass any of the following to connect:
+     * - group name
+     * - existing connection instance
+     * - array of database configuration values
+     *
+     * @param array|ConnectionInterface|string|null $db
+     *
+     * @throws ConfigException
+     */
+    public function __construct(MigrationsConfig $config, $db = null)
+    {
+        $this->enabled = $config->enabled ?? false;
+        $this->table   = $config->table ?? 'migrations';
+
+        // Default name space is the app namespace
+        $this->namespace = APP_NAMESPACE;
+
+        // get default database group
+        $config      = config('Database');
+        $this->group = $config->defaultGroup;
+        unset($config);
+
+        // If no db connection passed in, use
+        // default database group.
+        $this->db = db_connect($db);
+    }
+
+    /**
+     * Locate and run all new migrations
+     *
+     * @throws ConfigException
+     * @throws RuntimeException
+     *
+     * @return bool
+     */
+    public function latest(?string $group = null)
+    {
+        if (! $this->enabled) {
+            throw ConfigException::forDisabledMigrations();
+        }
+
+        $this->ensureTable();
+
+        if ($group !== null) {
+            $this->groupFilter = $group;
+            $this->setGroup($group);
+        }
+
+        $migrations = $this->findMigrations();
+
+        if (empty($migrations)) {
+            return true;
+        }
+
+        foreach ($this->getHistory((string) $group) as $history) {
+            unset($migrations[$this->getObjectUid($history)]);
+        }
+
+        $batch = $this->getLastBatch() + 1;
+
+        foreach ($migrations as $migration) {
+            if ($this->migrate('up', $migration)) {
+                if ($this->groupSkip === true) {
+                    $this->groupSkip = false;
+
+                    continue;
+                }
+
+                $this->addHistory($migration, $batch);
+            } else {
+                $this->regress(-1);
+
+                $message = lang('Migrations.generalFault');
+
+                if ($this->silent) {
+                    $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                    return false;
+                }
+
+                throw new RuntimeException($message);
+            }
+        }
+
+        $data           = get_object_vars($this);
+        $data['method'] = 'latest';
+        Events::trigger('migrate', $data);
+
+        return true;
+    }
+
+    /**
+     * Migrate down to a previous batch
+     *
+     * Calls each migration step required to get to the provided batch
+     *
+     * @param int $targetBatch Target batch number, or negative for a relative batch, 0 for all
+     *
+     * @throws ConfigException
+     * @throws RuntimeException
+     *
+     * @return mixed Current batch number on success, FALSE on failure or no migrations are found
+     */
+    public function regress(int $targetBatch = 0, ?string $group = null)
+    {
+        if (! $this->enabled) {
+            throw ConfigException::forDisabledMigrations();
+        }
+
+        // Set database group if not null
+        if ($group !== null) {
+            $this->setGroup($group);
+        }
+
+        $this->ensureTable();
+
+        $batches = $this->getBatches();
+
+        if ($targetBatch < 0) {
+            $targetBatch = $batches[count($batches) - 1 + $targetBatch] ?? 0;
+        }
+
+        if (empty($batches) && $targetBatch === 0) {
+            return true;
+        }
+
+        if ($targetBatch !== 0 && ! in_array($targetBatch, $batches, true)) {
+            $message = lang('Migrations.batchNotFound') . $targetBatch;
+
+            if ($this->silent) {
+                $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                return false;
+            }
+
+            throw new RuntimeException($message);
+        }
+
+        $tmpNamespace = $this->namespace;
+
+        $this->namespace = null;
+        $allMigrations   = $this->findMigrations();
+
+        $migrations = [];
+
+        while ($batch = array_pop($batches)) {
+            if ($batch <= $targetBatch) {
+                break;
+            }
+
+            foreach ($this->getBatchHistory($batch, 'desc') as $history) {
+                $uid = $this->getObjectUid($history);
+
+                if (! isset($allMigrations[$uid])) {
+                    $message = lang('Migrations.gap') . ' ' . $history->version;
+
+                    if ($this->silent) {
+                        $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                        return false;
+                    }
+
+                    throw new RuntimeException($message);
+                }
+
+                $migration          = $allMigrations[$uid];
+                $migration->history = $history;
+                $migrations[]       = $migration;
+            }
+        }
+
+        foreach ($migrations as $migration) {
+            if ($this->migrate('down', $migration)) {
+                $this->removeHistory($migration->history);
+            } else {
+                $message = lang('Migrations.generalFault');
+
+                if ($this->silent) {
+                    $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                    return false;
+                }
+
+                throw new RuntimeException($message);
+            }
+        }
+
+        $data           = get_object_vars($this);
+        $data['method'] = 'regress';
+        Events::trigger('migrate', $data);
+
+        $this->namespace = $tmpNamespace;
+
+        return true;
+    }
+
+    /**
+     * Migrate a single file regardless of order or batches.
+     * Method "up" or "down" determined by presence in history.
+     * NOTE: This is not recommended and provided mostly for testing.
+     *
+     * @param string $path Full path to a valid migration file
+     * @param string $path Namespace of the target migration
+     */
+    public function force(string $path, string $namespace, ?string $group = null)
+    {
+        if (! $this->enabled) {
+            throw ConfigException::forDisabledMigrations();
+        }
+
+        $this->ensureTable();
+
+        if ($group !== null) {
+            $this->groupFilter = $group;
+            $this->setGroup($group);
+        }
+
+        $migration = $this->migrationFromFile($path, $namespace);
+        if (empty($migration)) {
+            $message = lang('Migrations.notFound');
+
+            if ($this->silent) {
+                $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                return false;
+            }
+
+            throw new RuntimeException($message);
+        }
+
+        $method = 'up';
+        $this->setNamespace($migration->namespace);
+
+        foreach ($this->getHistory($this->group) as $history) {
+            if ($this->getObjectUid($history) === $migration->uid) {
+                $method             = 'down';
+                $migration->history = $history;
+                break;
+            }
+        }
+
+        if ($method === 'up') {
+            $batch = $this->getLastBatch() + 1;
+
+            if ($this->migrate('up', $migration) && $this->groupSkip === false) {
+                $this->addHistory($migration, $batch);
+
+                return true;
+            }
+
+            $this->groupSkip = false;
+        } elseif ($this->migrate('down', $migration)) {
+            $this->removeHistory($migration->history);
+
+            return true;
+        }
+
+        $message = lang('Migrations.generalFault');
+
+        if ($this->silent) {
+            $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+            return false;
+        }
+
+        throw new RuntimeException($message);
+    }
+
+    /**
+     * Retrieves list of available migration scripts
+     *
+     * @return array List of all located migrations by their UID
+     */
+    public function findMigrations(): array
+    {
+        $namespaces = $this->namespace ? [$this->namespace] : array_keys(Services::autoloader()->getNamespace());
+        $migrations = [];
+
+        foreach ($namespaces as $namespace) {
+            foreach ($this->findNamespaceMigrations($namespace) as $migration) {
+                $migrations[$migration->uid] = $migration;
+            }
+        }
+
+        // Sort migrations ascending by their UID (version)
+        ksort($migrations);
+
+        return $migrations;
+    }
+
+    /**
+     * Retrieves a list of available migration scripts for one namespace
+     */
+    public function findNamespaceMigrations(string $namespace): array
+    {
+        $migrations = [];
+        $locator    = Services::locator(true);
+
+        if (! empty($this->path)) {
+            helper('filesystem');
+            $dir   = rtrim($this->path, DIRECTORY_SEPARATOR) . '/';
+            $files = get_filenames($dir, true);
+        } else {
+            $files = $locator->listNamespaceFiles($namespace, '/Database/Migrations/');
+        }
+
+        foreach ($files as $file) {
+            $file = empty($this->path) ? $file : $this->path . str_replace($this->path, '', $file);
+
+            if ($migration = $this->migrationFromFile($file, $namespace)) {
+                $migrations[] = $migration;
+            }
+        }
+
+        return $migrations;
+    }
+
+    /**
+     * Create a migration object from a file path.
+     *
+     * @return false|object Returns the migration object, or false on failure
+     */
+    protected function migrationFromFile(string $path, string $namespace)
+    {
+        if (substr($path, -4) !== '.php') {
+            return false;
+        }
+
+        $name = basename($path, '.php');
+
+        if (! preg_match($this->regex, $name)) {
+            return false;
+        }
+
+        $locator = Services::locator(true);
+
+        $migration = new stdClass();
+
+        $migration->version   = $this->getMigrationNumber($name);
+        $migration->name      = $this->getMigrationName($name);
+        $migration->path      = $path;
+        $migration->class     = $locator->getClassname($path);
+        $migration->namespace = $namespace;
+        $migration->uid       = $this->getObjectUid($migration);
+
+        return $migration;
+    }
+
+    /**
+     * Allows other scripts to modify on the fly as needed.
+     *
+     * @return MigrationRunner
+     */
+    public function setNamespace(?string $namespace)
+    {
+        $this->namespace = $namespace;
+
+        return $this;
+    }
+
+    /**
+     * Allows other scripts to modify on the fly as needed.
+     *
+     * @return MigrationRunner
+     */
+    public function setGroup(string $group)
+    {
+        $this->group = $group;
+
+        return $this;
+    }
+
+    /**
+     * @return MigrationRunner
+     */
+    public function setName(string $name)
+    {
+        $this->name = $name;
+
+        return $this;
+    }
+
+    /**
+     * If $silent == true, then will not throw exceptions and will
+     * attempt to continue gracefully.
+     *
+     * @return MigrationRunner
+     */
+    public function setSilent(bool $silent)
+    {
+        $this->silent = $silent;
+
+        return $this;
+    }
+
+    /**
+     * Extracts the migration number from a filename
+     */
+    protected function getMigrationNumber(string $migration): string
+    {
+        preg_match('/^\d{4}[_-]?\d{2}[_-]?\d{2}[_-]?\d{6}/', $migration, $matches);
+
+        return count($matches) ? $matches[0] : '0';
+    }
+
+    /**
+     * Extracts the migration class name from a filename
+     */
+    protected function getMigrationName(string $migration): string
+    {
+        $parts = explode('_', $migration);
+        array_shift($parts);
+
+        return implode('_', $parts);
+    }
+
+    /**
+     * Uses the non-repeatable portions of a migration or history
+     * to create a sortable unique key
+     *
+     * @param object $object migration or $history
+     */
+    public function getObjectUid($object): string
+    {
+        return preg_replace('/[^0-9]/', '', $object->version) . $object->class;
+    }
+
+    /**
+     * Retrieves messages formatted for CLI output
+     */
+    public function getCliMessages(): array
+    {
+        return $this->cliMessages;
+    }
+
+    /**
+     * Clears any CLI messages.
+     *
+     * @return MigrationRunner
+     */
+    public function clearCliMessages()
+    {
+        $this->cliMessages = [];
+
+        return $this;
+    }
+
+    /**
+     * Truncates the history table.
+     */
+    public function clearHistory()
+    {
+        if ($this->db->tableExists($this->table)) {
+            $this->db->table($this->table)->truncate();
+        }
+    }
+
+    /**
+     * Add a history to the table.
+     *
+     * @param object $migration
+     */
+    protected function addHistory($migration, int $batch)
+    {
+        $this->db->table($this->table)->insert([
+            'version'   => $migration->version,
+            'class'     => $migration->class,
+            'group'     => $this->group,
+            'namespace' => $migration->namespace,
+            'time'      => time(),
+            'batch'     => $batch,
+        ]);
+
+        if (is_cli()) {
+            $this->cliMessages[] = sprintf(
+                "\t%s(%s) %s_%s",
+                CLI::color(lang('Migrations.added'), 'yellow'),
+                $migration->namespace,
+                $migration->version,
+                $migration->class
+            );
+        }
+    }
+
+    /**
+     * Removes a single history
+     *
+     * @param object $history
+     */
+    protected function removeHistory($history)
+    {
+        $this->db->table($this->table)->where('id', $history->id)->delete();
+
+        if (is_cli()) {
+            $this->cliMessages[] = sprintf(
+                "\t%s(%s) %s_%s",
+                CLI::color(lang('Migrations.removed'), 'yellow'),
+                $history->namespace,
+                $history->version,
+                $history->class
+            );
+        }
+    }
+
+    /**
+     * Grabs the full migration history from the database for a group
+     */
+    public function getHistory(string $group = 'default'): array
+    {
+        $this->ensureTable();
+
+        $builder = $this->db->table($this->table);
+
+        // If group was specified then use it
+        if (! empty($group)) {
+            $builder->where('group', $group);
+        }
+
+        // If a namespace was specified then use it
+        if ($this->namespace) {
+            $builder->where('namespace', $this->namespace);
+        }
+
+        $query = $builder->orderBy('id', 'ASC')->get();
+
+        return ! empty($query) ? $query->getResultObject() : [];
+    }
+
+    /**
+     * Returns the migration history for a single batch.
+     *
+     * @param string $order
+     */
+    public function getBatchHistory(int $batch, $order = 'asc'): array
+    {
+        $this->ensureTable();
+
+        $query = $this->db->table($this->table)
+            ->where('batch', $batch)
+            ->orderBy('id', $order)
+            ->get();
+
+        return ! empty($query) ? $query->getResultObject() : [];
+    }
+
+    /**
+     * Returns all the batches from the database history in order
+     */
+    public function getBatches(): array
+    {
+        $this->ensureTable();
+
+        $batches = $this->db->table($this->table)
+            ->select('batch')
+            ->distinct()
+            ->orderBy('batch', 'asc')
+            ->get()
+            ->getResultArray();
+
+        return array_map('intval', array_column($batches, 'batch'));
+    }
+
+    /**
+     * Returns the value of the last batch in the database.
+     */
+    public function getLastBatch(): int
+    {
+        $this->ensureTable();
+
+        $batch = $this->db->table($this->table)
+            ->selectMax('batch')
+            ->get()
+            ->getResultObject();
+
+        $batch = is_array($batch) && count($batch)
+            ? end($batch)->batch
+            : 0;
+
+        return (int) $batch;
+    }
+
+    /**
+     * Returns the version number of the first migration for a batch.
+     * Mostly just for tests.
+     */
+    public function getBatchStart(int $batch): string
+    {
+        if ($batch < 0) {
+            $batches = $this->getBatches();
+            $batch   = $batches[count($batches) - 1] ?? 0;
+        }
+
+        $migration = $this->db->table($this->table)
+            ->where('batch', $batch)
+            ->orderBy('id', 'asc')
+            ->limit(1)
+            ->get()
+            ->getResultObject();
+
+        return count($migration) ? $migration[0]->version : '0';
+    }
+
+    /**
+     * Returns the version number of the last migration for a batch.
+     * Mostly just for tests.
+     */
+    public function getBatchEnd(int $batch): string
+    {
+        if ($batch < 0) {
+            $batches = $this->getBatches();
+            $batch   = $batches[count($batches) - 1] ?? 0;
+        }
+
+        $migration = $this->db->table($this->table)
+            ->where('batch', $batch)
+            ->orderBy('id', 'desc')
+            ->limit(1)
+            ->get()
+            ->getResultObject();
+
+        return count($migration) ? $migration[0]->version : 0;
+    }
+
+    /**
+     * Ensures that we have created our migrations table
+     * in the database.
+     */
+    public function ensureTable()
+    {
+        if ($this->tableChecked || $this->db->tableExists($this->table)) {
+            return;
+        }
+
+        $forge = Database::forge($this->db);
+
+        $forge->addField([
+            'id' => [
+                'type'           => 'BIGINT',
+                'constraint'     => 20,
+                'unsigned'       => true,
+                'auto_increment' => true,
+            ],
+            'version' => [
+                'type'       => 'VARCHAR',
+                'constraint' => 255,
+                'null'       => false,
+            ],
+            'class' => [
+                'type'       => 'VARCHAR',
+                'constraint' => 255,
+                'null'       => false,
+            ],
+            'group' => [
+                'type'       => 'VARCHAR',
+                'constraint' => 255,
+                'null'       => false,
+            ],
+            'namespace' => [
+                'type'       => 'VARCHAR',
+                'constraint' => 255,
+                'null'       => false,
+            ],
+            'time' => [
+                'type'       => 'INT',
+                'constraint' => 11,
+                'null'       => false,
+            ],
+            'batch' => [
+                'type'       => 'INT',
+                'constraint' => 11,
+                'unsigned'   => true,
+                'null'       => false,
+            ],
+        ]);
+
+        $forge->addPrimaryKey('id');
+        $forge->createTable($this->table, true);
+
+        $this->tableChecked = true;
+    }
+
+    /**
+     * Handles the actual running of a migration.
+     *
+     * @param string $direction "up" or "down"
+     * @param object $migration The migration to run
+     */
+    protected function migrate($direction, $migration): bool
+    {
+        include_once $migration->path;
+
+        $class = $migration->class;
+        $this->setName($migration->name);
+
+        // Validate the migration file structure
+        if (! class_exists($class, false)) {
+            $message = sprintf(lang('Migrations.classNotFound'), $class);
+
+            if ($this->silent) {
+                $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                return false;
+            }
+
+            throw new RuntimeException($message);
+        }
+
+        $instance = new $class();
+        $group    = $instance->getDBGroup() ?? config('Database')->defaultGroup;
+
+        if (ENVIRONMENT !== 'testing' && $group === 'tests' && $this->groupFilter !== 'tests') {
+            // @codeCoverageIgnoreStart
+            $this->groupSkip = true;
+
+            return true;
+            // @codeCoverageIgnoreEnd
+        }
+
+        if ($direction === 'up' && $this->groupFilter !== null && $this->groupFilter !== $group) {
+            $this->groupSkip = true;
+
+            return true;
+        }
+
+        $this->setGroup($group);
+
+        if (! is_callable([$instance, $direction])) {
+            $message = sprintf(lang('Migrations.missingMethod'), $direction);
+
+            if ($this->silent) {
+                $this->cliMessages[] = "\t" . CLI::color($message, 'red');
+
+                return false;
+            }
+
+            throw new RuntimeException($message);
+        }
+
+        $instance->{$direction}();
+
+        return true;
+    }
+}

system/Database/ModelFactory.php

@@ -0,0 +1,52 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\Config\Factories;
+
+/**
+ * Returns new or shared Model instances
+ *
+ * @deprecated Use CodeIgniter\Config\Factories::models()
+ *
+ * @codeCoverageIgnore
+ */
+class ModelFactory
+{
+    /**
+     * Creates new Model instances or returns a shared instance
+     *
+     * @return mixed
+     */
+    public static function get(string $name, bool $getShared = true, ?ConnectionInterface $connection = null)
+    {
+        return Factories::models($name, ['getShared' => $getShared], $connection);
+    }
+
+    /**
+     * Helper method for injecting mock instances while testing.
+     *
+     * @param object $instance
+     */
+    public static function injectMock(string $name, $instance)
+    {
+        Factories::injectMock('models', $name, $instance);
+    }
+
+    /**
+     * Resets the static arrays
+     */
+    public static function reset()
+    {
+        Factories::reset('models');
+    }
+}

system/Database/MySQLi/Builder.php

@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use CodeIgniter\Database\BaseBuilder;
+
+/**
+ * Builder for MySQLi
+ */
+class Builder extends BaseBuilder
+{
+    /**
+     * Identifier escape character
+     *
+     * @var string
+     */
+    protected $escapeChar = '`';
+
+    /**
+     * Specifies which sql statements
+     * support the ignore option.
+     *
+     * @var array
+     */
+    protected $supportedIgnoreStatements = [
+        'update' => 'IGNORE',
+        'insert' => 'IGNORE',
+        'delete' => 'IGNORE',
+    ];
+
+    /**
+     * FROM tables
+     *
+     * Groups tables in FROM clauses if needed, so there is no confusion
+     * about operator precedence.
+     *
+     * Note: This is only used (and overridden) by MySQL.
+     */
+    protected function _fromTables(): string
+    {
+        if (! empty($this->QBJoin) && count($this->QBFrom) > 1) {
+            return '(' . implode(', ', $this->QBFrom) . ')';
+        }
+
+        return implode(', ', $this->QBFrom);
+    }
+}

system/Database/MySQLi/Connection.php

@@ -0,0 +1,605 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use LogicException;
+use MySQLi;
+use mysqli_sql_exception;
+use stdClass;
+use Throwable;
+
+/**
+ * Connection for MySQLi
+ */
+class Connection extends BaseConnection
+{
+    /**
+     * Database driver
+     *
+     * @var string
+     */
+    public $DBDriver = 'MySQLi';
+
+    /**
+     * DELETE hack flag
+     *
+     * Whether to use the MySQL "delete hack" which allows the number
+     * of affected rows to be shown. Uses a preg_replace when enabled,
+     * adding a bit more processing to all queries.
+     *
+     * @var bool
+     */
+    public $deleteHack = true;
+
+    /**
+     * Identifier escape character
+     *
+     * @var string
+     */
+    public $escapeChar = '`';
+
+    /**
+     * MySQLi object
+     *
+     * Has to be preserved without being assigned to $conn_id.
+     *
+     * @var MySQLi
+     */
+    public $mysqli;
+
+    /**
+     * MySQLi constant
+     *
+     * For unbuffered queries use `MYSQLI_USE_RESULT`.
+     *
+     * Default mode for buffered queries uses `MYSQLI_STORE_RESULT`.
+     *
+     * @var int
+     */
+    public $resultMode = MYSQLI_STORE_RESULT;
+
+    /**
+     * Connect to the database.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function connect(bool $persistent = false)
+    {
+        // Do we have a socket path?
+        if ($this->hostname[0] === '/') {
+            $hostname = null;
+            $port     = null;
+            $socket   = $this->hostname;
+        } else {
+            $hostname = ($persistent === true) ? 'p:' . $this->hostname : $this->hostname;
+            $port     = empty($this->port) ? null : $this->port;
+            $socket   = '';
+        }
+
+        $clientFlags  = ($this->compress === true) ? MYSQLI_CLIENT_COMPRESS : 0;
+        $this->mysqli = mysqli_init();
+
+        mysqli_report(MYSQLI_REPORT_ALL & ~MYSQLI_REPORT_INDEX);
+
+        $this->mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);
+
+        if (isset($this->strictOn)) {
+            if ($this->strictOn) {
+                $this->mysqli->options(
+                    MYSQLI_INIT_COMMAND,
+                    "SET SESSION sql_mode = CONCAT(@@sql_mode, ',', 'STRICT_ALL_TABLES')"
+                );
+            } else {
+                $this->mysqli->options(
+                    MYSQLI_INIT_COMMAND,
+                    "SET SESSION sql_mode = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
+                                        @@sql_mode,
+                                        'STRICT_ALL_TABLES,', ''),
+                                    ',STRICT_ALL_TABLES', ''),
+                                'STRICT_ALL_TABLES', ''),
+                            'STRICT_TRANS_TABLES,', ''),
+                        ',STRICT_TRANS_TABLES', ''),
+                    'STRICT_TRANS_TABLES', '')"
+                );
+            }
+        }
+
+        if (is_array($this->encrypt)) {
+            $ssl = [];
+
+            if (! empty($this->encrypt['ssl_key'])) {
+                $ssl['key'] = $this->encrypt['ssl_key'];
+            }
+            if (! empty($this->encrypt['ssl_cert'])) {
+                $ssl['cert'] = $this->encrypt['ssl_cert'];
+            }
+            if (! empty($this->encrypt['ssl_ca'])) {
+                $ssl['ca'] = $this->encrypt['ssl_ca'];
+            }
+            if (! empty($this->encrypt['ssl_capath'])) {
+                $ssl['capath'] = $this->encrypt['ssl_capath'];
+            }
+            if (! empty($this->encrypt['ssl_cipher'])) {
+                $ssl['cipher'] = $this->encrypt['ssl_cipher'];
+            }
+
+            if (! empty($ssl)) {
+                if (isset($this->encrypt['ssl_verify'])) {
+                    if ($this->encrypt['ssl_verify']) {
+                        if (defined('MYSQLI_OPT_SSL_VERIFY_SERVER_CERT')) {
+                            $this->mysqli->options(MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, 1);
+                        }
+                    }
+                    // Apparently (when it exists), setting MYSQLI_OPT_SSL_VERIFY_SERVER_CERT
+                    // to FALSE didn't do anything, so PHP 5.6.16 introduced yet another
+                    // constant ...
+                    //
+                    // https://secure.php.net/ChangeLog-5.php#5.6.16
+                    // https://bugs.php.net/bug.php?id=68344
+                    elseif (defined('MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT') && version_compare($this->mysqli->client_info, 'mysqlnd 5.6', '>=')) {
+                        $clientFlags += MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT;
+                    }
+                }
+
+                $this->mysqli->ssl_set(
+                    $ssl['key'] ?? null,
+                    $ssl['cert'] ?? null,
+                    $ssl['ca'] ?? null,
+                    $ssl['capath'] ?? null,
+                    $ssl['cipher'] ?? null
+                );
+            }
+
+            $clientFlags += MYSQLI_CLIENT_SSL;
+        }
+
+        try {
+            if ($this->mysqli->real_connect(
+                $hostname,
+                $this->username,
+                $this->password,
+                $this->database,
+                $port,
+                $socket,
+                $clientFlags
+            )) {
+                // Prior to version 5.7.3, MySQL silently downgrades to an unencrypted connection if SSL setup fails
+                if (($clientFlags & MYSQLI_CLIENT_SSL) && version_compare($this->mysqli->client_info, 'mysqlnd 5.7.3', '<=')
+                    && empty($this->mysqli->query("SHOW STATUS LIKE 'ssl_cipher'")->fetch_object()->Value)
+                ) {
+                    $this->mysqli->close();
+                    $message = 'MySQLi was configured for an SSL connection, but got an unencrypted connection instead!';
+                    log_message('error', $message);
+
+                    if ($this->DBDebug) {
+                        throw new DatabaseException($message);
+                    }
+
+                    return false;
+                }
+
+                if (! $this->mysqli->set_charset($this->charset)) {
+                    log_message('error', "Database: Unable to set the configured connection charset ('{$this->charset}').");
+
+                    $this->mysqli->close();
+
+                    if ($this->DBDebug) {
+                        throw new DatabaseException('Unable to set client connection character set: ' . $this->charset);
+                    }
+
+                    return false;
+                }
+
+                return $this->mysqli;
+            }
+        } catch (Throwable $e) {
+            // Clean sensitive information from errors.
+            $msg = $e->getMessage();
+
+            $msg = str_replace($this->username, '****', $msg);
+            $msg = str_replace($this->password, '****', $msg);
+
+            throw new DatabaseException($msg, $e->getCode(), $e);
+        }
+
+        return false;
+    }
+
+    /**
+     * Keep or establish the connection if no queries have been sent for
+     * a length of time exceeding the server's idle timeout.
+     */
+    public function reconnect()
+    {
+        $this->close();
+        $this->initialize();
+    }
+
+    /**
+     * Close the database connection.
+     */
+    protected function _close()
+    {
+        $this->connID->close();
+    }
+
+    /**
+     * Select a specific database table to use.
+     */
+    public function setDatabase(string $databaseName): bool
+    {
+        if ($databaseName === '') {
+            $databaseName = $this->database;
+        }
+
+        if (empty($this->connID)) {
+            $this->initialize();
+        }
+
+        if ($this->connID->select_db($databaseName)) {
+            $this->database = $databaseName;
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Returns a string containing the version of the database being used.
+     */
+    public function getVersion(): string
+    {
+        if (isset($this->dataCache['version'])) {
+            return $this->dataCache['version'];
+        }
+
+        if (empty($this->mysqli)) {
+            $this->initialize();
+        }
+
+        return $this->dataCache['version'] = $this->mysqli->server_info;
+    }
+
+    /**
+     * Executes the query against the database.
+     *
+     * @return mixed
+     */
+    protected function execute(string $sql)
+    {
+        while ($this->connID->more_results()) {
+            $this->connID->next_result();
+            if ($res = $this->connID->store_result()) {
+                $res->free();
+            }
+        }
+
+        try {
+            return $this->connID->query($this->prepQuery($sql), $this->resultMode);
+        } catch (mysqli_sql_exception $e) {
+            log_message('error', $e->getMessage());
+
+            if ($this->DBDebug) {
+                throw $e;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Prep the query. If needed, each database adapter can prep the query string
+     */
+    protected function prepQuery(string $sql): string
+    {
+        // mysqli_affected_rows() returns 0 for "DELETE FROM TABLE" queries. This hack
+        // modifies the query so that it a proper number of affected rows is returned.
+        if ($this->deleteHack === true && preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $sql)) {
+            return trim($sql) . ' WHERE 1=1';
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Returns the total number of rows affected by this query.
+     */
+    public function affectedRows(): int
+    {
+        return $this->connID->affected_rows ?? 0;
+    }
+
+    /**
+     * Platform-dependant string escape
+     */
+    protected function _escapeString(string $str): string
+    {
+        if (! $this->connID) {
+            $this->initialize();
+        }
+
+        return $this->connID->real_escape_string($str);
+    }
+
+    /**
+     * Escape Like String Direct
+     * There are a few instances where MySQLi queries cannot take the
+     * additional "ESCAPE x" parameter for specifying the escape character
+     * in "LIKE" strings, and this handles those directly with a backslash.
+     *
+     * @param string|string[] $str Input string
+     *
+     * @return string|string[]
+     */
+    public function escapeLikeStringDirect($str)
+    {
+        if (is_array($str)) {
+            foreach ($str as $key => $val) {
+                $str[$key] = $this->escapeLikeStringDirect($val);
+            }
+
+            return $str;
+        }
+
+        $str = $this->_escapeString($str);
+
+        // Escape LIKE condition wildcards
+        return str_replace(
+            [$this->likeEscapeChar, '%', '_'],
+            ['\\' . $this->likeEscapeChar, '\\' . '%', '\\' . '_'],
+            $str
+        );
+    }
+
+    /**
+     * Generates the SQL for listing tables in a platform-dependent manner.
+     * Uses escapeLikeStringDirect().
+     */
+    protected function _listTables(bool $prefixLimit = false): string
+    {
+        $sql = 'SHOW TABLES FROM ' . $this->escapeIdentifiers($this->database);
+
+        if ($prefixLimit !== false && $this->DBPrefix !== '') {
+            return $sql . " LIKE '" . $this->escapeLikeStringDirect($this->DBPrefix) . "%'";
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Generates a platform-specific query string so that the column names can be fetched.
+     */
+    protected function _listColumns(string $table = ''): string
+    {
+        return 'SHOW COLUMNS FROM ' . $this->protectIdentifiers($table, true, null, false);
+    }
+
+    /**
+     * Returns an array of objects with field data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _fieldData(string $table): array
+    {
+        $table = $this->protectIdentifiers($table, true, null, false);
+
+        if (($query = $this->query('SHOW COLUMNS FROM ' . $table)) === false) {
+            throw new DatabaseException(lang('Database.failGetFieldData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        for ($i = 0, $c = count($query); $i < $c; $i++) {
+            $retVal[$i]       = new stdClass();
+            $retVal[$i]->name = $query[$i]->Field;
+
+            sscanf($query[$i]->Type, '%[a-z](%d)', $retVal[$i]->type, $retVal[$i]->max_length);
+
+            $retVal[$i]->nullable    = $query[$i]->Null === 'YES';
+            $retVal[$i]->default     = $query[$i]->Default;
+            $retVal[$i]->primary_key = (int) ($query[$i]->Key === 'PRI');
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with index data
+     *
+     * @throws DatabaseException
+     * @throws LogicException
+     *
+     * @return stdClass[]
+     */
+    protected function _indexData(string $table): array
+    {
+        $table = $this->protectIdentifiers($table, true, null, false);
+
+        if (($query = $this->query('SHOW INDEX FROM ' . $table)) === false) {
+            throw new DatabaseException(lang('Database.failGetIndexData'));
+        }
+
+        if (! $indexes = $query->getResultArray()) {
+            return [];
+        }
+
+        $keys = [];
+
+        foreach ($indexes as $index) {
+            if (empty($keys[$index['Key_name']])) {
+                $keys[$index['Key_name']]       = new stdClass();
+                $keys[$index['Key_name']]->name = $index['Key_name'];
+
+                if ($index['Key_name'] === 'PRIMARY') {
+                    $type = 'PRIMARY';
+                } elseif ($index['Index_type'] === 'FULLTEXT') {
+                    $type = 'FULLTEXT';
+                } elseif ($index['Non_unique']) {
+                    $type = $index['Index_type'] === 'SPATIAL' ? 'SPATIAL' : 'INDEX';
+                } else {
+                    $type = 'UNIQUE';
+                }
+
+                $keys[$index['Key_name']]->type = $type;
+            }
+
+            $keys[$index['Key_name']]->fields[] = $index['Column_name'];
+        }
+
+        return $keys;
+    }
+
+    /**
+     * Returns an array of objects with Foreign key data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _foreignKeyData(string $table): array
+    {
+        $sql = '
+                    SELECT
+                        tc.CONSTRAINT_NAME,
+                        tc.TABLE_NAME,
+                        kcu.COLUMN_NAME,
+                        rc.REFERENCED_TABLE_NAME,
+                        kcu.REFERENCED_COLUMN_NAME
+                    FROM information_schema.TABLE_CONSTRAINTS AS tc
+                    INNER JOIN information_schema.REFERENTIAL_CONSTRAINTS AS rc
+                        ON tc.CONSTRAINT_NAME = rc.CONSTRAINT_NAME
+                        AND tc.CONSTRAINT_SCHEMA = rc.CONSTRAINT_SCHEMA
+                    INNER JOIN information_schema.KEY_COLUMN_USAGE AS kcu
+                        ON tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
+                        AND tc.CONSTRAINT_SCHEMA = kcu.CONSTRAINT_SCHEMA
+                    WHERE
+                        tc.CONSTRAINT_TYPE = ' . $this->escape('FOREIGN KEY') . ' AND
+                        tc.TABLE_SCHEMA = ' . $this->escape($this->database) . ' AND
+                        tc.TABLE_NAME = ' . $this->escape($table);
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetForeignKeyData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj                      = new stdClass();
+            $obj->constraint_name     = $row->CONSTRAINT_NAME;
+            $obj->table_name          = $row->TABLE_NAME;
+            $obj->column_name         = $row->COLUMN_NAME;
+            $obj->foreign_table_name  = $row->REFERENCED_TABLE_NAME;
+            $obj->foreign_column_name = $row->REFERENCED_COLUMN_NAME;
+
+            $retVal[] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns platform-specific SQL to disable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _disableForeignKeyChecks()
+    {
+        return 'SET FOREIGN_KEY_CHECKS=0';
+    }
+
+    /**
+     * Returns platform-specific SQL to enable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _enableForeignKeyChecks()
+    {
+        return 'SET FOREIGN_KEY_CHECKS=1';
+    }
+
+    /**
+     * Returns the last error code and message.
+     * Must return this format: ['code' => string|int, 'message' => string]
+     * intval(code) === 0 means "no error".
+     *
+     * @return array<string, int|string>
+     */
+    public function error(): array
+    {
+        if (! empty($this->mysqli->connect_errno)) {
+            return [
+                'code'    => $this->mysqli->connect_errno,
+                'message' => $this->mysqli->connect_error,
+            ];
+        }
+
+        return [
+            'code'    => $this->connID->errno,
+            'message' => $this->connID->error,
+        ];
+    }
+
+    /**
+     * Insert ID
+     */
+    public function insertID(): int
+    {
+        return $this->connID->insert_id;
+    }
+
+    /**
+     * Begin Transaction
+     */
+    protected function _transBegin(): bool
+    {
+        $this->connID->autocommit(false);
+
+        return $this->connID->begin_transaction();
+    }
+
+    /**
+     * Commit Transaction
+     */
+    protected function _transCommit(): bool
+    {
+        if ($this->connID->commit()) {
+            $this->connID->autocommit(true);
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Rollback Transaction
+     */
+    protected function _transRollback(): bool
+    {
+        if ($this->connID->rollback()) {
+            $this->connID->autocommit(true);
+
+            return true;
+        }
+
+        return false;
+    }
+}

system/Database/MySQLi/Forge.php

@@ -0,0 +1,239 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use CodeIgniter\Database\Forge as BaseForge;
+
+/**
+ * Forge for MySQLi
+ */
+class Forge extends BaseForge
+{
+    /**
+     * CREATE DATABASE statement
+     *
+     * @var string
+     */
+    protected $createDatabaseStr = 'CREATE DATABASE %s CHARACTER SET %s COLLATE %s';
+
+    /**
+     * CREATE DATABASE IF statement
+     *
+     * @var string
+     */
+    protected $createDatabaseIfStr = 'CREATE DATABASE IF NOT EXISTS %s CHARACTER SET %s COLLATE %s';
+
+    /**
+     * DROP CONSTRAINT statement
+     *
+     * @var string
+     */
+    protected $dropConstraintStr = 'ALTER TABLE %s DROP FOREIGN KEY %s';
+
+    /**
+     * CREATE TABLE keys flag
+     *
+     * Whether table keys are created from within the
+     * CREATE TABLE statement.
+     *
+     * @var bool
+     */
+    protected $createTableKeys = true;
+
+    /**
+     * UNSIGNED support
+     *
+     * @var array
+     */
+    protected $_unsigned = [
+        'TINYINT',
+        'SMALLINT',
+        'MEDIUMINT',
+        'INT',
+        'INTEGER',
+        'BIGINT',
+        'REAL',
+        'DOUBLE',
+        'DOUBLE PRECISION',
+        'FLOAT',
+        'DECIMAL',
+        'NUMERIC',
+    ];
+
+    /**
+     * Table Options list which required to be quoted
+     *
+     * @var array
+     */
+    protected $_quoted_table_options = [
+        'COMMENT',
+        'COMPRESSION',
+        'CONNECTION',
+        'DATA DIRECTORY',
+        'INDEX DIRECTORY',
+        'ENCRYPTION',
+        'PASSWORD',
+    ];
+
+    /**
+     * NULL value representation in CREATE/ALTER TABLE statements
+     *
+     * @var string
+     *
+     * @internal
+     */
+    protected $null = 'NULL';
+
+    /**
+     * CREATE TABLE attributes
+     *
+     * @param array $attributes Associative array of table attributes
+     */
+    protected function _createTableAttributes(array $attributes): string
+    {
+        $sql = '';
+
+        foreach (array_keys($attributes) as $key) {
+            if (is_string($key)) {
+                $sql .= ' ' . strtoupper($key) . ' = ';
+
+                if (in_array(strtoupper($key), $this->_quoted_table_options, true)) {
+                    $sql .= $this->db->escape($attributes[$key]);
+                } else {
+                    $sql .= $this->db->escapeString($attributes[$key]);
+                }
+            }
+        }
+
+        if (! empty($this->db->charset) && ! strpos($sql, 'CHARACTER SET') && ! strpos($sql, 'CHARSET')) {
+            $sql .= ' DEFAULT CHARACTER SET = ' . $this->db->escapeString($this->db->charset);
+        }
+
+        if (! empty($this->db->DBCollat) && ! strpos($sql, 'COLLATE')) {
+            $sql .= ' COLLATE = ' . $this->db->escapeString($this->db->DBCollat);
+        }
+
+        return $sql;
+    }
+
+    /**
+     * ALTER TABLE
+     *
+     * @param string $alterType ALTER type
+     * @param string $table     Table name
+     * @param mixed  $field     Column definition
+     *
+     * @return string|string[]
+     */
+    protected function _alterTable(string $alterType, string $table, $field)
+    {
+        if ($alterType === 'DROP') {
+            return parent::_alterTable($alterType, $table, $field);
+        }
+
+        $sql = 'ALTER TABLE ' . $this->db->escapeIdentifiers($table);
+
+        foreach ($field as $i => $data) {
+            if ($data['_literal'] !== false) {
+                $field[$i] = ($alterType === 'ADD') ? "\n\tADD " . $data['_literal'] : "\n\tMODIFY " . $data['_literal'];
+            } else {
+                if ($alterType === 'ADD') {
+                    $field[$i]['_literal'] = "\n\tADD ";
+                } else {
+                    $field[$i]['_literal'] = empty($data['new_name']) ? "\n\tMODIFY " : "\n\tCHANGE ";
+                }
+
+                $field[$i] = $field[$i]['_literal'] . $this->_processColumn($field[$i]);
+            }
+        }
+
+        return [$sql . implode(',', $field)];
+    }
+
+    /**
+     * Process column
+     */
+    protected function _processColumn(array $field): string
+    {
+        $extraClause = isset($field['after']) ? ' AFTER ' . $this->db->escapeIdentifiers($field['after']) : '';
+
+        if (empty($extraClause) && isset($field['first']) && $field['first'] === true) {
+            $extraClause = ' FIRST';
+        }
+
+        return $this->db->escapeIdentifiers($field['name'])
+                . (empty($field['new_name']) ? '' : ' ' . $this->db->escapeIdentifiers($field['new_name']))
+                . ' ' . $field['type'] . $field['length']
+                . $field['unsigned']
+                . $field['null']
+                . $field['default']
+                . $field['auto_increment']
+                . $field['unique']
+                . (empty($field['comment']) ? '' : ' COMMENT ' . $field['comment'])
+                . $extraClause;
+    }
+
+    /**
+     * Process indexes
+     *
+     * @param string $table (ignored)
+     */
+    protected function _processIndexes(string $table): string
+    {
+        $sql = '';
+
+        for ($i = 0, $c = count($this->keys); $i < $c; $i++) {
+            if (is_array($this->keys[$i])) {
+                for ($i2 = 0, $c2 = count($this->keys[$i]); $i2 < $c2; $i2++) {
+                    if (! isset($this->fields[$this->keys[$i][$i2]])) {
+                        unset($this->keys[$i][$i2]);
+
+                        continue;
+                    }
+                }
+            } elseif (! isset($this->fields[$this->keys[$i]])) {
+                unset($this->keys[$i]);
+
+                continue;
+            }
+
+            if (! is_array($this->keys[$i])) {
+                $this->keys[$i] = [$this->keys[$i]];
+            }
+
+            $unique = in_array($i, $this->uniqueKeys, true) ? 'UNIQUE ' : '';
+
+            $sql .= ",\n\t{$unique}KEY " . $this->db->escapeIdentifiers(implode('_', $this->keys[$i]))
+                . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ')';
+        }
+
+        $this->keys = [];
+
+        return $sql;
+    }
+
+    /**
+     * Drop Key
+     *
+     * @return bool
+     */
+    public function dropKey(string $table, string $keyName)
+    {
+        $sql = sprintf(
+            $this->dropIndexStr,
+            $this->db->escapeIdentifiers($keyName),
+            $this->db->escapeIdentifiers($this->db->DBPrefix . $table),
+        );
+
+        return $this->db->query($sql);
+    }
+}

system/Database/MySQLi/PreparedQuery.php

@@ -0,0 +1,87 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use BadMethodCallException;
+use CodeIgniter\Database\BasePreparedQuery;
+
+/**
+ * Prepared query for MySQLi
+ */
+class PreparedQuery extends BasePreparedQuery
+{
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * NOTE: This version is based on SQL code. Child classes should
+     * override this method.
+     *
+     * @param array $options Passed to the connection's prepare statement.
+     *                       Unused in the MySQLi driver.
+     *
+     * @return mixed
+     */
+    public function _prepare(string $sql, array $options = [])
+    {
+        // Mysqli driver doesn't like statements
+        // with terminating semicolons.
+        $sql = rtrim($sql, ';');
+
+        if (! $this->statement = $this->db->mysqli->prepare($sql)) {
+            $this->errorCode   = $this->db->mysqli->errno;
+            $this->errorString = $this->db->mysqli->error;
+        }
+
+        return $this;
+    }
+
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     */
+    public function _execute(array $data): bool
+    {
+        if (! isset($this->statement)) {
+            throw new BadMethodCallException('You must call prepare before trying to execute a prepared statement.');
+        }
+
+        // First off -bind the parameters
+        $bindTypes = '';
+
+        // Determine the type string
+        foreach ($data as $item) {
+            if (is_int($item)) {
+                $bindTypes .= 'i';
+            } elseif (is_numeric($item)) {
+                $bindTypes .= 'd';
+            } else {
+                $bindTypes .= 's';
+            }
+        }
+
+        // Bind it
+        $this->statement->bind_param($bindTypes, ...$data);
+
+        return $this->statement->execute();
+    }
+
+    /**
+     * Returns the result object for the prepared query.
+     *
+     * @return mixed
+     */
+    public function _getResult()
+    {
+        return $this->statement->get_result();
+    }
+}

system/Database/MySQLi/Result.php

@@ -0,0 +1,162 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use CodeIgniter\Database\BaseResult;
+use CodeIgniter\Entity\Entity;
+use stdClass;
+
+/**
+ * Result for MySQLi
+ */
+class Result extends BaseResult
+{
+    /**
+     * Gets the number of fields in the result set.
+     */
+    public function getFieldCount(): int
+    {
+        return $this->resultID->field_count;
+    }
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    public function getFieldNames(): array
+    {
+        $fieldNames = [];
+        $this->resultID->field_seek(0);
+
+        while ($field = $this->resultID->fetch_field()) {
+            $fieldNames[] = $field->name;
+        }
+
+        return $fieldNames;
+    }
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    public function getFieldData(): array
+    {
+        static $dataTypes = [
+            MYSQLI_TYPE_DECIMAL    => 'decimal',
+            MYSQLI_TYPE_NEWDECIMAL => 'newdecimal',
+            MYSQLI_TYPE_FLOAT      => 'float',
+            MYSQLI_TYPE_DOUBLE     => 'double',
+
+            MYSQLI_TYPE_BIT      => 'bit',
+            MYSQLI_TYPE_SHORT    => 'short',
+            MYSQLI_TYPE_LONG     => 'long',
+            MYSQLI_TYPE_LONGLONG => 'longlong',
+            MYSQLI_TYPE_INT24    => 'int24',
+
+            MYSQLI_TYPE_YEAR => 'year',
+
+            MYSQLI_TYPE_TIMESTAMP => 'timestamp',
+            MYSQLI_TYPE_DATE      => 'date',
+            MYSQLI_TYPE_TIME      => 'time',
+            MYSQLI_TYPE_DATETIME  => 'datetime',
+            MYSQLI_TYPE_NEWDATE   => 'newdate',
+
+            MYSQLI_TYPE_SET => 'set',
+
+            MYSQLI_TYPE_VAR_STRING => 'var_string',
+            MYSQLI_TYPE_STRING     => 'string',
+
+            MYSQLI_TYPE_GEOMETRY    => 'geometry',
+            MYSQLI_TYPE_TINY_BLOB   => 'tiny_blob',
+            MYSQLI_TYPE_MEDIUM_BLOB => 'medium_blob',
+            MYSQLI_TYPE_LONG_BLOB   => 'long_blob',
+            MYSQLI_TYPE_BLOB        => 'blob',
+        ];
+
+        $retVal    = [];
+        $fieldData = $this->resultID->fetch_fields();
+
+        foreach ($fieldData as $i => $data) {
+            $retVal[$i]              = new stdClass();
+            $retVal[$i]->name        = $data->name;
+            $retVal[$i]->type        = $data->type;
+            $retVal[$i]->type_name   = in_array($data->type, [1, 247], true) ? 'char' : ($dataTypes[$data->type] ?? null);
+            $retVal[$i]->max_length  = $data->max_length;
+            $retVal[$i]->primary_key = $data->flags & 2;
+            $retVal[$i]->length      = $data->length;
+            $retVal[$i]->default     = $data->def;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Frees the current result.
+     */
+    public function freeResult()
+    {
+        if (is_object($this->resultID)) {
+            $this->resultID->free();
+            $this->resultID = false;
+        }
+    }
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @return mixed
+     */
+    public function dataSeek(int $n = 0)
+    {
+        return $this->resultID->data_seek($n);
+    }
+
+    /**
+     * Returns the result set as an array.
+     *
+     * Overridden by driver classes.
+     *
+     * @return mixed
+     */
+    protected function fetchAssoc()
+    {
+        return $this->resultID->fetch_assoc();
+    }
+
+    /**
+     * Returns the result set as an object.
+     *
+     * Overridden by child classes.
+     *
+     * @return bool|Entity|object
+     */
+    protected function fetchObject(string $className = 'stdClass')
+    {
+        if (is_subclass_of($className, Entity::class)) {
+            return empty($data = $this->fetchAssoc()) ? false : (new $className())->setAttributes($data);
+        }
+
+        return $this->resultID->fetch_object($className);
+    }
+
+    /**
+     * Returns the number of rows in the resultID (i.e., mysqli_result object)
+     */
+    public function getNumRows(): int
+    {
+        if (! is_int($this->numRows)) {
+            $this->numRows = $this->resultID->num_rows;
+        }
+
+        return $this->numRows;
+    }
+}

system/Database/MySQLi/Utils.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\MySQLi;
+
+use CodeIgniter\Database\BaseUtils;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Utils for MySQLi
+ */
+class Utils extends BaseUtils
+{
+    /**
+     * List databases statement
+     *
+     * @var string
+     */
+    protected $listDatabases = 'SHOW DATABASES';
+
+    /**
+     * OPTIMIZE TABLE statement
+     *
+     * @var string
+     */
+    protected $optimizeTable = 'OPTIMIZE TABLE %s';
+
+    /**
+     * Platform dependent version of the backup function.
+     *
+     * @return mixed
+     */
+    public function _backup(?array $prefs = null)
+    {
+        throw new DatabaseException('Unsupported feature of the database platform you are using.');
+    }
+}

system/Database/Postgre/Builder.php

@@ -0,0 +1,313 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use CodeIgniter\Database\BaseBuilder;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Builder for Postgre
+ */
+class Builder extends BaseBuilder
+{
+    /**
+     * ORDER BY random keyword
+     *
+     * @var array
+     */
+    protected $randomKeyword = [
+        'RANDOM()',
+    ];
+
+    /**
+     * Specifies which sql statements
+     * support the ignore option.
+     *
+     * @var array
+     */
+    protected $supportedIgnoreStatements = [
+        'insert' => 'ON CONFLICT DO NOTHING',
+    ];
+
+    /**
+     * Checks if the ignore option is supported by
+     * the Database Driver for the specific statement.
+     *
+     * @return string
+     */
+    protected function compileIgnore(string $statement)
+    {
+        $sql = parent::compileIgnore($statement);
+
+        if (! empty($sql)) {
+            $sql = ' ' . trim($sql);
+        }
+
+        return $sql;
+    }
+
+    /**
+     * ORDER BY
+     *
+     * @param string $direction ASC, DESC or RANDOM
+     *
+     * @return BaseBuilder
+     */
+    public function orderBy(string $orderBy, string $direction = '', ?bool $escape = null)
+    {
+        $direction = strtoupper(trim($direction));
+        if ($direction === 'RANDOM') {
+            if (ctype_digit($orderBy)) {
+                $orderBy = (float) ($orderBy > 1 ? "0.{$orderBy}" : $orderBy);
+            }
+
+            if (is_float($orderBy)) {
+                $this->db->simpleQuery("SET SEED {$orderBy}");
+            }
+
+            $orderBy   = $this->randomKeyword[0];
+            $direction = '';
+            $escape    = false;
+        }
+
+        return parent::orderBy($orderBy, $direction, $escape);
+    }
+
+    /**
+     * Increments a numeric column by the specified value.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function increment(string $column, int $value = 1)
+    {
+        $column = $this->db->protectIdentifiers($column);
+
+        $sql = $this->_update($this->QBFrom[0], [$column => "to_number({$column}, '9999999') + {$value}"]);
+
+        return $this->db->query($sql, $this->binds, false);
+    }
+
+    /**
+     * Decrements a numeric column by the specified value.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function decrement(string $column, int $value = 1)
+    {
+        $column = $this->db->protectIdentifiers($column);
+
+        $sql = $this->_update($this->QBFrom[0], [$column => "to_number({$column}, '9999999') - {$value}"]);
+
+        return $this->db->query($sql, $this->binds, false);
+    }
+
+    /**
+     * Compiles an replace into string and runs the query.
+     * Because PostgreSQL doesn't support the replace into command,
+     * we simply do a DELETE and an INSERT on the first key/value
+     * combo, assuming that it's either the primary key or a unique key.
+     *
+     * @param array|null $set An associative array of insert values
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function replace(?array $set = null)
+    {
+        if ($set !== null) {
+            $this->set($set);
+        }
+
+        if (! $this->QBSet) {
+            if (CI_DEBUG) {
+                throw new DatabaseException('You must use the "set" method to update an entry.');
+            }
+
+            return false; // @codeCoverageIgnore
+        }
+
+        $table = $this->QBFrom[0];
+        $set   = $this->binds;
+
+        array_walk($set, static function (array &$item) {
+            $item = $item[0];
+        });
+
+        $key   = array_key_first($set);
+        $value = $set[$key];
+
+        $builder = $this->db->table($table);
+        $exists  = $builder->where($key, $value, true)->get()->getFirstRow();
+
+        if (empty($exists) && $this->testMode) {
+            $result = $this->getCompiledInsert();
+        } elseif (empty($exists)) {
+            $result = $builder->insert($set);
+        } elseif ($this->testMode) {
+            $result = $this->where($key, $value, true)->getCompiledUpdate();
+        } else {
+            array_shift($set);
+            $result = $builder->where($key, $value, true)->update($set);
+        }
+
+        unset($builder);
+        $this->resetWrite();
+
+        return $result;
+    }
+
+    /**
+     * Generates a platform-specific insert string from the supplied data
+     */
+    protected function _insert(string $table, array $keys, array $unescapedKeys): string
+    {
+        return trim(sprintf('INSERT INTO %s (%s) VALUES (%s) %s', $table, implode(', ', $keys), implode(', ', $unescapedKeys), $this->compileIgnore('insert')));
+    }
+
+    /**
+     * Generates a platform-specific insert string from the supplied data.
+     */
+    protected function _insertBatch(string $table, array $keys, array $values): string
+    {
+        return trim(sprintf('INSERT INTO %s (%s) VALUES %s %s', $table, implode(', ', $keys), implode(', ', $values), $this->compileIgnore('insert')));
+    }
+
+    /**
+     * Compiles a delete string and runs the query
+     *
+     * @param mixed $where
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function delete($where = '', ?int $limit = null, bool $resetData = true)
+    {
+        if (! empty($limit) || ! empty($this->QBLimit)) {
+            throw new DatabaseException('PostgreSQL does not allow LIMITs on DELETE queries.');
+        }
+
+        return parent::delete($where, $limit, $resetData);
+    }
+
+    /**
+     * Generates a platform-specific LIMIT clause.
+     */
+    protected function _limit(string $sql, bool $offsetIgnore = false): string
+    {
+        return $sql . ' LIMIT ' . $this->QBLimit . ($this->QBOffset ? " OFFSET {$this->QBOffset}" : '');
+    }
+
+    /**
+     * Generates a platform-specific update string from the supplied data
+     *
+     * @throws DatabaseException
+     */
+    protected function _update(string $table, array $values): string
+    {
+        if (! empty($this->QBLimit)) {
+            throw new DatabaseException('Postgres does not support LIMITs with UPDATE queries.');
+        }
+
+        $this->QBOrderBy = [];
+
+        return parent::_update($table, $values);
+    }
+
+    /**
+     * Generates a platform-specific batch update string from the supplied data
+     */
+    protected function _updateBatch(string $table, array $values, string $index): string
+    {
+        $ids   = [];
+        $final = [];
+
+        foreach ($values as $val) {
+            $ids[] = $val[$index];
+
+            foreach (array_keys($val) as $field) {
+                if ($field !== $index) {
+                    $final[$field] = $final[$field] ?? [];
+
+                    $final[$field][] = "WHEN {$val[$index]} THEN {$val[$field]}";
+                }
+            }
+        }
+
+        $cases = '';
+
+        foreach ($final as $k => $v) {
+            $cases .= "{$k} = (CASE {$index}\n"
+                    . implode("\n", $v)
+                    . "\nELSE {$k} END), ";
+        }
+
+        $this->where("{$index} IN(" . implode(',', $ids) . ')', null, false);
+
+        return "UPDATE {$table} SET " . substr($cases, 0, -2) . $this->compileWhereHaving('QBWhere');
+    }
+
+    /**
+     * Generates a platform-specific delete string from the supplied data
+     */
+    protected function _delete(string $table): string
+    {
+        $this->QBLimit = false;
+
+        return parent::_delete($table);
+    }
+
+    /**
+     * Generates a platform-specific truncate string from the supplied data
+     *
+     * If the database does not support the truncate() command,
+     * then this method maps to 'DELETE FROM table'
+     */
+    protected function _truncate(string $table): string
+    {
+        return 'TRUNCATE ' . $table . ' RESTART IDENTITY';
+    }
+
+    /**
+     * Platform independent LIKE statement builder.
+     *
+     * In PostgreSQL, the ILIKE operator will perform case insensitive
+     * searches according to the current locale.
+     *
+     * @see https://www.postgresql.org/docs/9.2/static/functions-matching.html
+     */
+    protected function _like_statement(?string $prefix, string $column, ?string $not, string $bind, bool $insensitiveSearch = false): string
+    {
+        $op = $insensitiveSearch === true ? 'ILIKE' : 'LIKE';
+
+        return "{$prefix} {$column} {$not} {$op} :{$bind}:";
+    }
+
+    /**
+     * Generates the JOIN portion of the query
+     *
+     * @return BaseBuilder
+     */
+    public function join(string $table, string $cond, string $type = '', ?bool $escape = null)
+    {
+        if (! in_array('FULL OUTER', $this->joinTypes, true)) {
+            $this->joinTypes = array_merge($this->joinTypes, ['FULL OUTER']);
+        }
+
+        return parent::join($table, $cond, $type, $escape);
+    }
+}

system/Database/Postgre/Connection.php

@@ -0,0 +1,517 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use ErrorException;
+use stdClass;
+
+/**
+ * Connection for Postgre
+ */
+class Connection extends BaseConnection
+{
+    /**
+     * Database driver
+     *
+     * @var string
+     */
+    public $DBDriver = 'Postgre';
+
+    /**
+     * Database schema
+     *
+     * @var string
+     */
+    public $schema = 'public';
+
+    /**
+     * Identifier escape character
+     *
+     * @var string
+     */
+    public $escapeChar = '"';
+
+    /**
+     * Connect to the database.
+     *
+     * @return mixed
+     */
+    public function connect(bool $persistent = false)
+    {
+        if (empty($this->DSN)) {
+            $this->buildDSN();
+        }
+
+        // Strip pgsql if exists
+        if (mb_strpos($this->DSN, 'pgsql:') === 0) {
+            $this->DSN = mb_substr($this->DSN, 6);
+        }
+
+        // Convert semicolons to spaces.
+        $this->DSN = str_replace(';', ' ', $this->DSN);
+
+        $this->connID = $persistent === true ? pg_pconnect($this->DSN) : pg_connect($this->DSN);
+
+        if ($this->connID !== false) {
+            if ($persistent === true && pg_connection_status($this->connID) === PGSQL_CONNECTION_BAD && pg_ping($this->connID) === false
+            ) {
+                return false;
+            }
+
+            if (! empty($this->schema)) {
+                $this->simpleQuery("SET search_path TO {$this->schema},public");
+            }
+
+            if ($this->setClientEncoding($this->charset) === false) {
+                return false;
+            }
+        }
+
+        return $this->connID;
+    }
+
+    /**
+     * Keep or establish the connection if no queries have been sent for
+     * a length of time exceeding the server's idle timeout.
+     */
+    public function reconnect()
+    {
+        if (pg_ping($this->connID) === false) {
+            $this->connID = false;
+        }
+    }
+
+    /**
+     * Close the database connection.
+     */
+    protected function _close()
+    {
+        pg_close($this->connID);
+    }
+
+    /**
+     * Select a specific database table to use.
+     */
+    public function setDatabase(string $databaseName): bool
+    {
+        return false;
+    }
+
+    /**
+     * Returns a string containing the version of the database being used.
+     */
+    public function getVersion(): string
+    {
+        if (isset($this->dataCache['version'])) {
+            return $this->dataCache['version'];
+        }
+
+        if (! $this->connID || ($pgVersion = pg_version($this->connID)) === false) {
+            $this->initialize();
+        }
+
+        return isset($pgVersion['server']) ? $this->dataCache['version'] = $pgVersion['server'] : false;
+    }
+
+    /**
+     * Executes the query against the database.
+     *
+     * @return mixed
+     */
+    protected function execute(string $sql)
+    {
+        try {
+            return pg_query($this->connID, $sql);
+        } catch (ErrorException $e) {
+            log_message('error', $e);
+            if ($this->DBDebug) {
+                throw $e;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Get the prefix of the function to access the DB.
+     */
+    protected function getDriverFunctionPrefix(): string
+    {
+        return 'pg_';
+    }
+
+    /**
+     * Returns the total number of rows affected by this query.
+     */
+    public function affectedRows(): int
+    {
+        return pg_affected_rows($this->resultID);
+    }
+
+    /**
+     * "Smart" Escape String
+     *
+     * Escapes data based on type
+     *
+     * @param mixed $str
+     *
+     * @return mixed
+     */
+    public function escape($str)
+    {
+        if (! $this->connID) {
+            $this->initialize();
+        }
+
+        if (is_string($str) || (is_object($str) && method_exists($str, '__toString'))) {
+            return pg_escape_literal($this->connID, $str);
+        }
+
+        if (is_bool($str)) {
+            return $str ? 'TRUE' : 'FALSE';
+        }
+
+        return parent::escape($str);
+    }
+
+    /**
+     * Platform-dependant string escape
+     */
+    protected function _escapeString(string $str): string
+    {
+        if (! $this->connID) {
+            $this->initialize();
+        }
+
+        return pg_escape_string($this->connID, $str);
+    }
+
+    /**
+     * Generates the SQL for listing tables in a platform-dependent manner.
+     */
+    protected function _listTables(bool $prefixLimit = false): string
+    {
+        $sql = 'SELECT "table_name" FROM "information_schema"."tables" WHERE "table_schema" = \'' . $this->schema . "'";
+
+        if ($prefixLimit !== false && $this->DBPrefix !== '') {
+            return $sql . ' AND "table_name" LIKE \''
+                . $this->escapeLikeString($this->DBPrefix) . "%' "
+                . sprintf($this->likeEscapeStr, $this->likeEscapeChar);
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Generates a platform-specific query string so that the column names can be fetched.
+     */
+    protected function _listColumns(string $table = ''): string
+    {
+        return 'SELECT "column_name"
+			FROM "information_schema"."columns"
+			WHERE LOWER("table_name") = '
+                . $this->escape($this->DBPrefix . strtolower($table))
+                . ' ORDER BY "ordinal_position"';
+    }
+
+    /**
+     * Returns an array of objects with field data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _fieldData(string $table): array
+    {
+        $sql = 'SELECT "column_name", "data_type", "character_maximum_length", "numeric_precision", "column_default"
+			FROM "information_schema"."columns"
+			WHERE LOWER("table_name") = '
+                . $this->escape(strtolower($table))
+                . ' ORDER BY "ordinal_position"';
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetFieldData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        for ($i = 0, $c = count($query); $i < $c; $i++) {
+            $retVal[$i] = new stdClass();
+
+            $retVal[$i]->name       = $query[$i]->column_name;
+            $retVal[$i]->type       = $query[$i]->data_type;
+            $retVal[$i]->default    = $query[$i]->column_default;
+            $retVal[$i]->max_length = $query[$i]->character_maximum_length > 0 ? $query[$i]->character_maximum_length : $query[$i]->numeric_precision;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with index data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _indexData(string $table): array
+    {
+        $sql = 'SELECT "indexname", "indexdef"
+			FROM "pg_indexes"
+			WHERE LOWER("tablename") = ' . $this->escape(strtolower($table)) . '
+			AND "schemaname" = ' . $this->escape('public');
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetIndexData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj         = new stdClass();
+            $obj->name   = $row->indexname;
+            $_fields     = explode(',', preg_replace('/^.*\((.+?)\)$/', '$1', trim($row->indexdef)));
+            $obj->fields = array_map(static function ($v) {
+                return trim($v);
+            }, $_fields);
+
+            if (strpos($row->indexdef, 'CREATE UNIQUE INDEX pk') === 0) {
+                $obj->type = 'PRIMARY';
+            } else {
+                $obj->type = (strpos($row->indexdef, 'CREATE UNIQUE') === 0) ? 'UNIQUE' : 'INDEX';
+            }
+
+            $retVal[$obj->name] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with Foreign key data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _foreignKeyData(string $table): array
+    {
+        $sql = 'SELECT
+            tc.constraint_name, tc.table_name, kcu.column_name,
+            ccu.table_name AS foreign_table_name,
+            ccu.column_name AS foreign_column_name
+        FROM information_schema.table_constraints AS tc
+        JOIN information_schema.key_column_usage AS kcu
+            ON tc.constraint_name = kcu.constraint_name
+        JOIN information_schema.constraint_column_usage AS ccu
+            ON ccu.constraint_name = tc.constraint_name
+        WHERE constraint_type = ' . $this->escape('FOREIGN KEY') . ' AND
+            tc.table_name = ' . $this->escape($table);
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetForeignKeyData'));
+        }
+
+        $query  = $query->getResultObject();
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj = new stdClass();
+
+            $obj->constraint_name     = $row->constraint_name;
+            $obj->table_name          = $row->table_name;
+            $obj->column_name         = $row->column_name;
+            $obj->foreign_table_name  = $row->foreign_table_name;
+            $obj->foreign_column_name = $row->foreign_column_name;
+
+            $retVal[] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns platform-specific SQL to disable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _disableForeignKeyChecks()
+    {
+        return 'SET CONSTRAINTS ALL DEFERRED';
+    }
+
+    /**
+     * Returns platform-specific SQL to enable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _enableForeignKeyChecks()
+    {
+        return 'SET CONSTRAINTS ALL IMMEDIATE;';
+    }
+
+    /**
+     * Returns the last error code and message.
+     * Must return this format: ['code' => string|int, 'message' => string]
+     * intval(code) === 0 means "no error".
+     *
+     * @return array<string, int|string>
+     */
+    public function error(): array
+    {
+        return [
+            'code'    => '',
+            'message' => pg_last_error($this->connID) ?: '',
+        ];
+    }
+
+    /**
+     * @return int|string
+     */
+    public function insertID()
+    {
+        $v = pg_version($this->connID);
+        // 'server' key is only available since PostgreSQL 7.4
+        $v = explode(' ', $v['server'])[0] ?? 0;
+
+        $table  = func_num_args() > 0 ? func_get_arg(0) : null;
+        $column = func_num_args() > 1 ? func_get_arg(1) : null;
+
+        if ($table === null && $v >= '8.1') {
+            $sql = 'SELECT LASTVAL() AS ins_id';
+        } elseif ($table !== null) {
+            if ($column !== null && $v >= '8.0') {
+                $sql   = "SELECT pg_get_serial_sequence('{$table}', '{$column}') AS seq";
+                $query = $this->query($sql);
+                $query = $query->getRow();
+                $seq   = $query->seq;
+            } else {
+                // seq_name passed in table parameter
+                $seq = $table;
+            }
+
+            $sql = "SELECT CURRVAL('{$seq}') AS ins_id";
+        } else {
+            return pg_last_oid($this->resultID);
+        }
+
+        $query = $this->query($sql);
+        $query = $query->getRow();
+
+        return (int) $query->ins_id;
+    }
+
+    /**
+     * Build a DSN from the provided parameters
+     */
+    protected function buildDSN()
+    {
+        if ($this->DSN !== '') {
+            $this->DSN = '';
+        }
+
+        // If UNIX sockets are used, we shouldn't set a port
+        if (strpos($this->hostname, '/') !== false) {
+            $this->port = '';
+        }
+
+        if ($this->hostname !== '') {
+            $this->DSN = "host={$this->hostname} ";
+        }
+
+        // ctype_digit only accepts strings
+        $port = (string) $this->port;
+
+        if ($port !== '' && ctype_digit($port)) {
+            $this->DSN .= "port={$port} ";
+        }
+
+        if ($this->username !== '') {
+            $this->DSN .= "user={$this->username} ";
+
+            // An empty password is valid!
+            // password must be set to null to ignore it.
+            if ($this->password !== null) {
+                $this->DSN .= "password='{$this->password}' ";
+            }
+        }
+
+        if ($this->database !== '') {
+            $this->DSN .= "dbname={$this->database} ";
+        }
+
+        // We don't have these options as elements in our standard configuration
+        // array, but they might be set by parse_url() if the configuration was
+        // provided via string> Example:
+        //
+        // Postgre://username:password@localhost:5432/database?connect_timeout=5&sslmode=1
+        foreach (['connect_timeout', 'options', 'sslmode', 'service'] as $key) {
+            if (isset($this->{$key}) && is_string($this->{$key}) && $this->{$key} !== '') {
+                $this->DSN .= "{$key}='{$this->{$key}}' ";
+            }
+        }
+
+        $this->DSN = rtrim($this->DSN);
+    }
+
+    /**
+     * Set client encoding
+     */
+    protected function setClientEncoding(string $charset): bool
+    {
+        return pg_set_client_encoding($this->connID, $charset) === 0;
+    }
+
+    /**
+     * Begin Transaction
+     */
+    protected function _transBegin(): bool
+    {
+        return (bool) pg_query($this->connID, 'BEGIN');
+    }
+
+    /**
+     * Commit Transaction
+     */
+    protected function _transCommit(): bool
+    {
+        return (bool) pg_query($this->connID, 'COMMIT');
+    }
+
+    /**
+     * Rollback Transaction
+     */
+    protected function _transRollback(): bool
+    {
+        return (bool) pg_query($this->connID, 'ROLLBACK');
+    }
+
+    /**
+     * Determines if a query is a "write" type.
+     *
+     * Overrides BaseConnection::isWriteType, adding additional read query types.
+     *
+     * @param mixed $sql
+     */
+    public function isWriteType($sql): bool
+    {
+        if (preg_match('#^(INSERT|UPDATE).*RETURNING\s.+(\,\s?.+)*$#is', $sql)) {
+            return false;
+        }
+
+        return parent::isWriteType($sql);
+    }
+}

system/Database/Postgre/Forge.php

@@ -0,0 +1,193 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use CodeIgniter\Database\Forge as BaseForge;
+
+/**
+ * Forge for Postgre
+ */
+class Forge extends BaseForge
+{
+    /**
+     * CHECK DATABASE EXIST statement
+     *
+     * @var string
+     */
+    protected $checkDatabaseExistStr = 'SELECT 1 FROM pg_database WHERE datname = ?';
+
+    /**
+     * DROP CONSTRAINT statement
+     *
+     * @var string
+     */
+    protected $dropConstraintStr = 'ALTER TABLE %s DROP CONSTRAINT %s';
+
+    /**
+     * DROP INDEX statement
+     *
+     * @var string
+     */
+    protected $dropIndexStr = 'DROP INDEX %s';
+
+    /**
+     * UNSIGNED support
+     *
+     * @var array
+     */
+    protected $_unsigned = [
+        'INT2'     => 'INTEGER',
+        'SMALLINT' => 'INTEGER',
+        'INT'      => 'BIGINT',
+        'INT4'     => 'BIGINT',
+        'INTEGER'  => 'BIGINT',
+        'INT8'     => 'NUMERIC',
+        'BIGINT'   => 'NUMERIC',
+        'REAL'     => 'DOUBLE PRECISION',
+        'FLOAT'    => 'DOUBLE PRECISION',
+    ];
+
+    /**
+     * NULL value representation in CREATE/ALTER TABLE statements
+     *
+     * @var string
+     *
+     * @internal
+     */
+    protected $null = 'NULL';
+
+    /**
+     * CREATE TABLE attributes
+     *
+     * @param array $attributes Associative array of table attributes
+     */
+    protected function _createTableAttributes(array $attributes): string
+    {
+        return '';
+    }
+
+    /**
+     * @param mixed $field
+     *
+     * @return array|bool|string
+     */
+    protected function _alterTable(string $alterType, string $table, $field)
+    {
+        if (in_array($alterType, ['DROP', 'ADD'], true)) {
+            return parent::_alterTable($alterType, $table, $field);
+        }
+
+        $sql  = 'ALTER TABLE ' . $this->db->escapeIdentifiers($table);
+        $sqls = [];
+
+        foreach ($field as $data) {
+            if ($data['_literal'] !== false) {
+                return false;
+            }
+
+            if (version_compare($this->db->getVersion(), '8', '>=') && isset($data['type'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . " TYPE {$data['type']}{$data['length']}";
+            }
+
+            if (! empty($data['default'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . " SET DEFAULT {$data['default']}";
+            }
+
+            if (isset($data['null'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . ($data['null'] === true ? ' DROP' : ' SET') . ' NOT NULL';
+            }
+
+            if (! empty($data['new_name'])) {
+                $sqls[] = $sql . ' RENAME COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . ' TO ' . $this->db->escapeIdentifiers($data['new_name']);
+            }
+
+            if (! empty($data['comment'])) {
+                $sqls[] = 'COMMENT ON COLUMN' . $this->db->escapeIdentifiers($table)
+                    . '.' . $this->db->escapeIdentifiers($data['name'])
+                    . " IS {$data['comment']}";
+            }
+        }
+
+        return $sqls;
+    }
+
+    /**
+     * Process column
+     */
+    protected function _processColumn(array $field): string
+    {
+        return $this->db->escapeIdentifiers($field['name'])
+            . ' ' . $field['type'] . $field['length']
+            . $field['default']
+            . $field['null']
+            . $field['auto_increment']
+            . $field['unique'];
+    }
+
+    /**
+     * Performs a data type mapping between different databases.
+     */
+    protected function _attributeType(array &$attributes)
+    {
+        // Reset field lengths for data types that don't support it
+        if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== false) {
+            $attributes['CONSTRAINT'] = null;
+        }
+
+        switch (strtoupper($attributes['TYPE'])) {
+            case 'TINYINT':
+                $attributes['TYPE']     = 'SMALLINT';
+                $attributes['UNSIGNED'] = false;
+                break;
+
+            case 'MEDIUMINT':
+                $attributes['TYPE']     = 'INTEGER';
+                $attributes['UNSIGNED'] = false;
+                break;
+
+            case 'DATETIME':
+                $attributes['TYPE'] = 'TIMESTAMP';
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Field attribute AUTO_INCREMENT
+     */
+    protected function _attributeAutoIncrement(array &$attributes, array &$field)
+    {
+        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true) {
+            $field['type'] = $field['type'] === 'NUMERIC' || $field['type'] === 'BIGINT' ? 'BIGSERIAL' : 'SERIAL';
+        }
+    }
+
+    /**
+     * Generates a platform-specific DROP TABLE string
+     */
+    protected function _dropTable(string $table, bool $ifExists, bool $cascade): string
+    {
+        $sql = parent::_dropTable($table, $ifExists, $cascade);
+
+        if ($cascade === true) {
+            $sql .= ' CASCADE';
+        }
+
+        return $sql;
+    }
+}

system/Database/Postgre/PreparedQuery.php

@@ -0,0 +1,111 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use BadMethodCallException;
+use CodeIgniter\Database\BasePreparedQuery;
+use Exception;
+
+/**
+ * Prepared query for Postgre
+ */
+class PreparedQuery extends BasePreparedQuery
+{
+    /**
+     * Stores the name this query can be
+     * used under by postgres. Only used internally.
+     *
+     * @var string
+     */
+    protected $name;
+
+    /**
+     * The result resource from a successful
+     * pg_exec. Or false.
+     *
+     * @var bool|Result
+     */
+    protected $result;
+
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * NOTE: This version is based on SQL code. Child classes should
+     * override this method.
+     *
+     * @param array $options Passed to the connection's prepare statement.
+     *                       Unused in the MySQLi driver.
+     *
+     * @throws Exception
+     *
+     * @return mixed
+     */
+    public function _prepare(string $sql, array $options = [])
+    {
+        $this->name = (string) random_int(1, 10000000000000000);
+
+        $sql = $this->parameterize($sql);
+
+        // Update the query object since the parameters are slightly different
+        // than what was put in.
+        $this->query->setQuery($sql);
+
+        if (! $this->statement = pg_prepare($this->db->connID, $this->name, $sql)) {
+            $this->errorCode   = 0;
+            $this->errorString = pg_last_error($this->db->connID);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     */
+    public function _execute(array $data): bool
+    {
+        if (! isset($this->statement)) {
+            throw new BadMethodCallException('You must call prepare before trying to execute a prepared statement.');
+        }
+
+        $this->result = pg_execute($this->db->connID, $this->name, $data);
+
+        return (bool) $this->result;
+    }
+
+    /**
+     * Returns the result object for the prepared query.
+     *
+     * @return mixed
+     */
+    public function _getResult()
+    {
+        return $this->result;
+    }
+
+    /**
+     * Replaces the ? placeholders with $1, $2, etc parameters for use
+     * within the prepared query.
+     */
+    public function parameterize(string $sql): string
+    {
+        // Track our current value
+        $count = 0;
+
+        return preg_replace_callback('/\?/', static function () use (&$count) {
+            $count++;
+
+            return "\${$count}";
+        }, $sql);
+    }
+}

system/Database/Postgre/Result.php

@@ -0,0 +1,128 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use CodeIgniter\Database\BaseResult;
+use CodeIgniter\Entity\Entity;
+use stdClass;
+
+/**
+ * Result for Postgre
+ */
+class Result extends BaseResult
+{
+    /**
+     * Gets the number of fields in the result set.
+     */
+    public function getFieldCount(): int
+    {
+        return pg_num_fields($this->resultID);
+    }
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    public function getFieldNames(): array
+    {
+        $fieldNames = [];
+
+        for ($i = 0, $c = $this->getFieldCount(); $i < $c; $i++) {
+            $fieldNames[] = pg_field_name($this->resultID, $i);
+        }
+
+        return $fieldNames;
+    }
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    public function getFieldData(): array
+    {
+        $retVal = [];
+
+        for ($i = 0, $c = $this->getFieldCount(); $i < $c; $i++) {
+            $retVal[$i]             = new stdClass();
+            $retVal[$i]->name       = pg_field_name($this->resultID, $i);
+            $retVal[$i]->type       = pg_field_type_oid($this->resultID, $i);
+            $retVal[$i]->type_name  = pg_field_type($this->resultID, $i);
+            $retVal[$i]->max_length = pg_field_size($this->resultID, $i);
+            $retVal[$i]->length     = $retVal[$i]->max_length;
+            // $retVal[$i]->primary_key = (int)($fieldData[$i]->flags & 2);
+            // $retVal[$i]->default     = $fieldData[$i]->def;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Frees the current result.
+     */
+    public function freeResult()
+    {
+        if ($this->resultID !== false) {
+            pg_free_result($this->resultID);
+            $this->resultID = false;
+        }
+    }
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @return mixed
+     */
+    public function dataSeek(int $n = 0)
+    {
+        return pg_result_seek($this->resultID, $n);
+    }
+
+    /**
+     * Returns the result set as an array.
+     *
+     * Overridden by driver classes.
+     *
+     * @return mixed
+     */
+    protected function fetchAssoc()
+    {
+        return pg_fetch_assoc($this->resultID);
+    }
+
+    /**
+     * Returns the result set as an object.
+     *
+     * Overridden by child classes.
+     *
+     * @return bool|Entity|object
+     */
+    protected function fetchObject(string $className = 'stdClass')
+    {
+        if (is_subclass_of($className, Entity::class)) {
+            return empty($data = $this->fetchAssoc()) ? false : (new $className())->setAttributes($data);
+        }
+
+        return pg_fetch_object($this->resultID, null, $className);
+    }
+
+    /**
+     * Returns the number of rows in the resultID (i.e., PostgreSQL query result resource)
+     */
+    public function getNumRows(): int
+    {
+        if (! is_int($this->numRows)) {
+            $this->numRows = pg_num_rows($this->resultID);
+        }
+
+        return $this->numRows;
+    }
+}

system/Database/Postgre/Utils.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Postgre;
+
+use CodeIgniter\Database\BaseUtils;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Utils for Postgre
+ */
+class Utils extends BaseUtils
+{
+    /**
+     * List databases statement
+     *
+     * @var string
+     */
+    protected $listDatabases = 'SELECT datname FROM pg_database';
+
+    /**
+     * OPTIMIZE TABLE statement
+     *
+     * @var string
+     */
+    protected $optimizeTable = 'REINDEX TABLE %s';
+
+    /**
+     * Platform dependent version of the backup function.
+     *
+     * @return mixed
+     */
+    public function _backup(?array $prefs = null)
+    {
+        throw new DatabaseException('Unsupported feature of the database platform you are using.');
+    }
+}

system/Database/PreparedQueryInterface.php

@@ -0,0 +1,54 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+/**
+ * Prepared query interface
+ */
+interface PreparedQueryInterface
+{
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     *
+     * @return ResultInterface
+     */
+    public function execute(...$data);
+
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * @return mixed
+     */
+    public function prepare(string $sql, array $options = []);
+
+    /**
+     * Explicity closes the statement.
+     */
+    public function close();
+
+    /**
+     * Returns the SQL that has been prepared.
+     */
+    public function getQueryString(): string;
+
+    /**
+     * Returns the error code created while executing this statement.
+     */
+    public function getErrorCode(): int;
+
+    /**
+     * Returns the error message created while executing this statement.
+     */
+    public function getErrorMessage(): string;
+}

system/Database/Query.php

@@ -0,0 +1,418 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+/**
+ * Query builder
+ */
+class Query implements QueryInterface
+{
+    /**
+     * The query string, as provided by the user.
+     *
+     * @var string
+     */
+    protected $originalQueryString;
+
+    /**
+     * The final query string after binding, etc.
+     *
+     * @var string
+     */
+    protected $finalQueryString;
+
+    /**
+     * The binds and their values used for binding.
+     *
+     * @var array
+     */
+    protected $binds = [];
+
+    /**
+     * Bind marker
+     *
+     * Character used to identify values in a prepared statement.
+     *
+     * @var string
+     */
+    protected $bindMarker = '?';
+
+    /**
+     * The start time in seconds with microseconds
+     * for when this query was executed.
+     *
+     * @var float|string
+     */
+    protected $startTime;
+
+    /**
+     * The end time in seconds with microseconds
+     * for when this query was executed.
+     *
+     * @var float
+     */
+    protected $endTime;
+
+    /**
+     * The error code, if any.
+     *
+     * @var int
+     */
+    protected $errorCode;
+
+    /**
+     * The error message, if any.
+     *
+     * @var string
+     */
+    protected $errorString;
+
+    /**
+     * Pointer to database connection.
+     * Mainly for escaping features.
+     *
+     * @var ConnectionInterface
+     */
+    public $db;
+
+    public function __construct(ConnectionInterface &$db)
+    {
+        $this->db = $db;
+    }
+
+    /**
+     * Sets the raw query string to use for this statement.
+     *
+     * @param mixed $binds
+     *
+     * @return $this
+     */
+    public function setQuery(string $sql, $binds = null, bool $setEscape = true)
+    {
+        $this->originalQueryString = $sql;
+
+        if ($binds !== null) {
+            if (! is_array($binds)) {
+                $binds = [$binds];
+            }
+
+            if ($setEscape) {
+                array_walk($binds, static function (&$item) {
+                    $item = [
+                        $item,
+                        true,
+                    ];
+                });
+            }
+            $this->binds = $binds;
+        }
+
+        return $this;
+    }
+
+    /**
+     * Will store the variables to bind into the query later.
+     *
+     * @return $this
+     */
+    public function setBinds(array $binds, bool $setEscape = true)
+    {
+        if ($setEscape) {
+            array_walk($binds, static function (&$item) {
+                $item = [$item, true];
+            });
+        }
+
+        $this->binds = $binds;
+
+        return $this;
+    }
+
+    /**
+     * Returns the final, processed query string after binding, etal
+     * has been performed.
+     */
+    public function getQuery(): string
+    {
+        if (empty($this->finalQueryString)) {
+            $this->finalQueryString = $this->originalQueryString;
+        }
+
+        $this->compileBinds();
+
+        return $this->finalQueryString;
+    }
+
+    /**
+     * Records the execution time of the statement using microtime(true)
+     * for it's start and end values. If no end value is present, will
+     * use the current time to determine total duration.
+     *
+     * @param float $end
+     *
+     * @return $this
+     */
+    public function setDuration(float $start, ?float $end = null)
+    {
+        $this->startTime = $start;
+
+        if ($end === null) {
+            $end = microtime(true);
+        }
+
+        $this->endTime = $end;
+
+        return $this;
+    }
+
+    /**
+     * Returns the start time in seconds with microseconds.
+     *
+     * @return float|string
+     */
+    public function getStartTime(bool $returnRaw = false, int $decimals = 6)
+    {
+        if ($returnRaw) {
+            return $this->startTime;
+        }
+
+        return number_format($this->startTime, $decimals);
+    }
+
+    /**
+     * Returns the duration of this query during execution, or null if
+     * the query has not been executed yet.
+     *
+     * @param int $decimals The accuracy of the returned time.
+     */
+    public function getDuration(int $decimals = 6): string
+    {
+        return number_format(($this->endTime - $this->startTime), $decimals);
+    }
+
+    /**
+     * Stores the error description that happened for this query.
+     *
+     * @return $this
+     */
+    public function setError(int $code, string $error)
+    {
+        $this->errorCode   = $code;
+        $this->errorString = $error;
+
+        return $this;
+    }
+
+    /**
+     * Reports whether this statement created an error not.
+     */
+    public function hasError(): bool
+    {
+        return ! empty($this->errorString);
+    }
+
+    /**
+     * Returns the error code created while executing this statement.
+     */
+    public function getErrorCode(): int
+    {
+        return $this->errorCode;
+    }
+
+    /**
+     * Returns the error message created while executing this statement.
+     */
+    public function getErrorMessage(): string
+    {
+        return $this->errorString;
+    }
+
+    /**
+     * Determines if the statement is a write-type query or not.
+     */
+    public function isWriteType(): bool
+    {
+        return $this->db->isWriteType($this->originalQueryString);
+    }
+
+    /**
+     * Swaps out one table prefix for a new one.
+     *
+     * @return $this
+     */
+    public function swapPrefix(string $orig, string $swap)
+    {
+        $sql = empty($this->finalQueryString) ? $this->originalQueryString : $this->finalQueryString;
+
+        $this->finalQueryString = preg_replace('/(\W)' . $orig . '(\S+?)/', '\\1' . $swap . '\\2', $sql);
+
+        return $this;
+    }
+
+    /**
+     * Returns the original SQL that was passed into the system.
+     */
+    public function getOriginalQuery(): string
+    {
+        return $this->originalQueryString;
+    }
+
+    /**
+     * Escapes and inserts any binds into the finalQueryString object.
+     *
+     * @see https://regex101.com/r/EUEhay/5
+     */
+    protected function compileBinds()
+    {
+        $sql   = $this->finalQueryString;
+        $binds = $this->binds;
+
+        if (empty($binds)) {
+            return;
+        }
+
+        if (is_int(array_key_first($binds))) {
+            $bindCount = count($binds);
+            $ml        = strlen($this->bindMarker);
+
+            $this->finalQueryString = $this->matchSimpleBinds($sql, $binds, $bindCount, $ml);
+        } else {
+            // Reverse the binds so that duplicate named binds
+            // will be processed prior to the original binds.
+            $binds = array_reverse($binds);
+
+            $this->finalQueryString = $this->matchNamedBinds($sql, $binds);
+        }
+    }
+
+    /**
+     * Match bindings
+     */
+    protected function matchNamedBinds(string $sql, array $binds): string
+    {
+        $replacers = [];
+
+        foreach ($binds as $placeholder => $value) {
+            // $value[1] contains the boolean whether should be escaped or not
+            $escapedValue = $value[1] ? $this->db->escape($value[0]) : $value[0];
+
+            // In order to correctly handle backlashes in saved strings
+            // we will need to preg_quote, so remove the wrapping escape characters
+            // otherwise it will get escaped.
+            if (is_array($value[0])) {
+                $escapedValue = '(' . implode(',', $escapedValue) . ')';
+            }
+
+            $replacers[":{$placeholder}:"] = $escapedValue;
+        }
+
+        return strtr($sql, $replacers);
+    }
+
+    /**
+     * Match bindings
+     */
+    protected function matchSimpleBinds(string $sql, array $binds, int $bindCount, int $ml): string
+    {
+        if ($c = preg_match_all("/'[^']*'/", $sql, $matches)) {
+            $c = preg_match_all('/' . preg_quote($this->bindMarker, '/') . '/i', str_replace($matches[0], str_replace($this->bindMarker, str_repeat(' ', $ml), $matches[0]), $sql, $c), $matches, PREG_OFFSET_CAPTURE);
+
+            // Bind values' count must match the count of markers in the query
+            if ($bindCount !== $c) {
+                return $sql;
+            }
+        } elseif (($c = preg_match_all('/' . preg_quote($this->bindMarker, '/') . '/i', $sql, $matches, PREG_OFFSET_CAPTURE)) !== $bindCount) {
+            return $sql;
+        }
+
+        do {
+            $c--;
+            $escapedValue = $binds[$c][1] ? $this->db->escape($binds[$c][0]) : $binds[$c][0];
+
+            if (is_array($escapedValue)) {
+                $escapedValue = '(' . implode(',', $escapedValue) . ')';
+            }
+
+            $sql = substr_replace($sql, $escapedValue, $matches[0][$c][1], $ml);
+        } while ($c !== 0);
+
+        return $sql;
+    }
+
+    /**
+     * Returns string to display in debug toolbar
+     */
+    public function debugToolbarDisplay(): string
+    {
+        // Key words we want bolded
+        static $highlight = [
+            'AND',
+            'AS',
+            'ASC',
+            'AVG',
+            'BY',
+            'COUNT',
+            'DESC',
+            'DISTINCT',
+            'FROM',
+            'GROUP',
+            'HAVING',
+            'IN',
+            'INNER',
+            'INSERT',
+            'INTO',
+            'IS',
+            'JOIN',
+            'LEFT',
+            'LIKE',
+            'LIMIT',
+            'MAX',
+            'MIN',
+            'NOT',
+            'NULL',
+            'OFFSET',
+            'ON',
+            'OR',
+            'ORDER',
+            'RIGHT',
+            'SELECT',
+            'SUM',
+            'UPDATE',
+            'VALUES',
+            'WHERE',
+        ];
+
+        if (empty($this->finalQueryString)) {
+            $this->compileBinds(); // @codeCoverageIgnore
+        }
+
+        $sql = esc($this->finalQueryString);
+
+        /**
+         * @see https://stackoverflow.com/a/20767160
+         * @see https://regex101.com/r/hUlrGN/4
+         */
+        $search = '/\b(?:' . implode('|', $highlight) . ')\b(?![^(&#039;)]*&#039;(?:(?:[^(&#039;)]*&#039;){2})*[^(&#039;)]*$)/';
+
+        return preg_replace_callback($search, static function ($matches) {
+            return '<strong>' . str_replace(' ', '&nbsp;', $matches[0]) . '</strong>';
+        }, $sql);
+    }
+
+    /**
+     * Return text representation of the query
+     */
+    public function __toString(): string
+    {
+        return $this->getQuery();
+    }
+}

system/Database/QueryInterface.php

@@ -0,0 +1,87 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+/**
+ * Interface QueryInterface
+ *
+ * Represents a single statement that can be executed against the database.
+ * Statements are platform-specific and can handle binding of binds.
+ */
+interface QueryInterface
+{
+    /**
+     * Sets the raw query string to use for this statement.
+     *
+     * @param mixed $binds
+     *
+     * @return mixed
+     */
+    public function setQuery(string $sql, $binds = null, bool $setEscape = true);
+
+    /**
+     * Returns the final, processed query string after binding, etal
+     * has been performed.
+     *
+     * @return mixed
+     */
+    public function getQuery();
+
+    /**
+     * Records the execution time of the statement using microtime(true)
+     * for it's start and end values. If no end value is present, will
+     * use the current time to determine total duration.
+     *
+     * @return mixed
+     */
+    public function setDuration(float $start, ?float $end = null);
+
+    /**
+     * Returns the duration of this query during execution, or null if
+     * the query has not been executed yet.
+     *
+     * @param int $decimals The accuracy of the returned time.
+     */
+    public function getDuration(int $decimals = 6): string;
+
+    /**
+     * Stores the error description that happened for this query.
+     */
+    public function setError(int $code, string $error);
+
+    /**
+     * Reports whether this statement created an error not.
+     */
+    public function hasError(): bool;
+
+    /**
+     * Returns the error code created while executing this statement.
+     */
+    public function getErrorCode(): int;
+
+    /**
+     * Returns the error message created while executing this statement.
+     */
+    public function getErrorMessage(): string;
+
+    /**
+     * Determines if the statement is a write-type query or not.
+     */
+    public function isWriteType(): bool;
+
+    /**
+     * Swaps out one table prefix for a new one.
+     *
+     * @return mixed
+     */
+    public function swapPrefix(string $orig, string $swap);
+}

system/Database/ResultInterface.php

@@ -0,0 +1,164 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+/**
+ * Interface ResultInterface
+ */
+interface ResultInterface
+{
+    /**
+     * Retrieve the results of the query. Typically an array of
+     * individual data rows, which can be either an 'array', an
+     * 'object', or a custom class name.
+     *
+     * @param string $type The row type. Either 'array', 'object', or a class name to use
+     */
+    public function getResult(string $type = 'object'): array;
+
+    /**
+     * Returns the results as an array of custom objects.
+     *
+     * @param string $className The name of the class to use.
+     *
+     * @return mixed
+     */
+    public function getCustomResultObject(string $className);
+
+    /**
+     * Returns the results as an array of arrays.
+     *
+     * If no results, an empty array is returned.
+     */
+    public function getResultArray(): array;
+
+    /**
+     * Returns the results as an array of objects.
+     *
+     * If no results, an empty array is returned.
+     */
+    public function getResultObject(): array;
+
+    /**
+     * Wrapper object to return a row as either an array, an object, or
+     * a custom class.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @param mixed  $n    The index of the results to return
+     * @param string $type The type of result object. 'array', 'object' or class name.
+     *
+     * @return mixed
+     */
+    public function getRow($n = 0, string $type = 'object');
+
+    /**
+     * Returns a row as a custom class instance.
+     *
+     * If row doesn't exists, returns null.
+     *
+     * @return mixed
+     */
+    public function getCustomRowObject(int $n, string $className);
+
+    /**
+     * Returns a single row from the results as an array.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @return mixed
+     */
+    public function getRowArray(int $n = 0);
+
+    /**
+     * Returns a single row from the results as an object.
+     *
+     * If row doesn't exist, returns null.
+     *
+     * @return mixed
+     */
+    public function getRowObject(int $n = 0);
+
+    /**
+     * Assigns an item into a particular column slot.
+     *
+     * @param string $key
+     * @param mixed  $value
+     *
+     * @return mixed
+     */
+    public function setRow($key, $value = null);
+
+    /**
+     * Returns the "first" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getFirstRow(string $type = 'object');
+
+    /**
+     * Returns the "last" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getLastRow(string $type = 'object');
+
+    /**
+     * Returns the "next" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getNextRow(string $type = 'object');
+
+    /**
+     * Returns the "previous" row of the current results.
+     *
+     * @return mixed
+     */
+    public function getPreviousRow(string $type = 'object');
+
+    /**
+     * Returns an unbuffered row and move the pointer to the next row.
+     *
+     * @return mixed
+     */
+    public function getUnbufferedRow(string $type = 'object');
+
+    /**
+     * Gets the number of fields in the result set.
+     */
+    public function getFieldCount(): int;
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    public function getFieldNames(): array;
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    public function getFieldData(): array;
+
+    /**
+     * Frees the current result.
+     */
+    public function freeResult();
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @return mixed
+     */
+    public function dataSeek(int $n = 0);
+}

system/Database/SQLSRV/Builder.php

@@ -0,0 +1,625 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use CodeIgniter\Database\BaseBuilder;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\DataException;
+use CodeIgniter\Database\ResultInterface;
+
+/**
+ * Builder for SQLSRV
+ *
+ * @todo auto check for TextCastToInt
+ * @todo auto check for InsertIndexValue
+ * @todo replace: delete index entries before insert
+ */
+class Builder extends BaseBuilder
+{
+    /**
+     * ORDER BY random keyword
+     *
+     * @var array
+     */
+    protected $randomKeyword = [
+        'NEWID()',
+        'RAND(%d)',
+    ];
+
+    /**
+     * Quoted identifier flag
+     *
+     * Whether to use SQL-92 standard quoted identifier
+     * (double quotes) or brackets for identifier escaping.
+     *
+     * @var bool
+     */
+    protected $_quoted_identifier = true;
+
+    /**
+     * Handle increment/decrement on text
+     *
+     * @var bool
+     */
+    public $castTextToInt = true;
+
+    /**
+     * Handle IDENTITY_INSERT property/
+     *
+     * @var bool
+     */
+    public $keyPermission = false;
+
+    /**
+     * Groups tables in FROM clauses if needed, so there is no confusion
+     * about operator precedence.
+     */
+    protected function _fromTables(): string
+    {
+        $from = [];
+
+        foreach ($this->QBFrom as $value) {
+            $from[] = $this->getFullName($value);
+        }
+
+        return implode(', ', $from);
+    }
+
+    /**
+     * Generates a platform-specific truncate string from the supplied data
+     *
+     * If the database does not support the truncate() command,
+     * then this method maps to 'DELETE FROM table'
+     */
+    protected function _truncate(string $table): string
+    {
+        return 'TRUNCATE TABLE ' . $this->getFullName($table);
+    }
+
+    /**
+     * Generates the JOIN portion of the query
+     *
+     * @return $this
+     */
+    public function join(string $table, string $cond, string $type = '', ?bool $escape = null)
+    {
+        if ($type !== '') {
+            $type = strtoupper(trim($type));
+
+            if (! in_array($type, $this->joinTypes, true)) {
+                $type = '';
+            } else {
+                $type .= ' ';
+            }
+        }
+
+        // Extract any aliases that might exist. We use this information
+        // in the protectIdentifiers to know whether to add a table prefix
+        $this->trackAliases($table);
+
+        if (! is_bool($escape)) {
+            $escape = $this->db->protectIdentifiers;
+        }
+
+        if (! $this->hasOperator($cond)) {
+            $cond = ' USING (' . ($escape ? $this->db->escapeIdentifiers($cond) : $cond) . ')';
+        } elseif ($escape === false) {
+            $cond = ' ON ' . $cond;
+        } else {
+            // Split multiple conditions
+            if (preg_match_all('/\sAND\s|\sOR\s/i', $cond, $joints, PREG_OFFSET_CAPTURE)) {
+                $conditions = [];
+                $joints     = $joints[0];
+                array_unshift($joints, ['', 0]);
+
+                for ($i = count($joints) - 1, $pos = strlen($cond); $i >= 0; $i--) {
+                    $joints[$i][1] += strlen($joints[$i][0]); // offset
+                    $conditions[$i] = substr($cond, $joints[$i][1], $pos - $joints[$i][1]);
+                    $pos            = $joints[$i][1] - strlen($joints[$i][0]);
+                    $joints[$i]     = $joints[$i][0];
+                }
+
+                ksort($conditions);
+            } else {
+                $conditions = [$cond];
+                $joints     = [''];
+            }
+
+            $cond = ' ON ';
+
+            foreach ($conditions as $i => $condition) {
+                $operator = $this->getOperator($condition);
+
+                $cond .= $joints[$i];
+                $cond .= preg_match('/(\(*)?([\[\]\w\.\'-]+)' . preg_quote($operator, '/') . '(.*)/i', $condition, $match) ? $match[1] . $this->db->protectIdentifiers($match[2]) . $operator . $this->db->protectIdentifiers($match[3]) : $condition;
+            }
+        }
+
+        // Do we want to escape the table name?
+        if ($escape === true) {
+            $table = $this->db->protectIdentifiers($table, true, null, false);
+        }
+
+        // Assemble the JOIN statement
+        $this->QBJoin[] = $type . 'JOIN ' . $this->getFullName($table) . $cond;
+
+        return $this;
+    }
+
+    /**
+     * Generates a platform-specific insert string from the supplied data
+     *
+     * @todo implement check for this instead static $insertKeyPermission
+     */
+    protected function _insert(string $table, array $keys, array $unescapedKeys): string
+    {
+        $fullTableName = $this->getFullName($table);
+
+        // insert statement
+        $statement = 'INSERT INTO ' . $fullTableName . ' (' . implode(',', $keys) . ') VALUES (' . implode(', ', $unescapedKeys) . ')';
+
+        return $this->keyPermission ? $this->addIdentity($fullTableName, $statement) : $statement;
+    }
+
+    /**
+     * Insert batch statement
+     *
+     * Generates a platform-specific insert string from the supplied data.
+     */
+    protected function _insertBatch(string $table, array $keys, array $values): string
+    {
+        return 'INSERT ' . $this->compileIgnore('insert') . 'INTO ' . $this->getFullName($table) . ' (' . implode(', ', $keys) . ') VALUES ' . implode(', ', $values);
+    }
+
+    /**
+     * Generates a platform-specific update string from the supplied data
+     */
+    protected function _update(string $table, array $values): string
+    {
+        $valstr = [];
+
+        foreach ($values as $key => $val) {
+            $valstr[] = $key . ' = ' . $val;
+        }
+
+        $fullTableName = $this->getFullName($table);
+
+        $statement = sprintf('UPDATE %s%s SET ', empty($this->QBLimit) ? '' : 'TOP(' . $this->QBLimit . ') ', $fullTableName);
+
+        $statement .= implode(', ', $valstr)
+            . $this->compileWhereHaving('QBWhere')
+            . $this->compileOrderBy();
+
+        return $this->keyPermission ? $this->addIdentity($fullTableName, $statement) : $statement;
+    }
+
+    /**
+     * Update_Batch statement
+     *
+     * Generates a platform-specific batch update string from the supplied data
+     */
+    protected function _updateBatch(string $table, array $values, string $index): string
+    {
+        $ids   = [];
+        $final = [];
+
+        foreach ($values as $val) {
+            $ids[] = $val[$index];
+
+            foreach (array_keys($val) as $field) {
+                if ($field !== $index) {
+                    $final[$field][] = 'WHEN ' . $index . ' = ' . $val[$index] . ' THEN ' . $val[$field];
+                }
+            }
+        }
+
+        $cases = '';
+
+        foreach ($final as $k => $v) {
+            $cases .= $k . " = CASE \n"
+                . implode("\n", $v) . "\n"
+                . 'ELSE ' . $k . ' END, ';
+        }
+
+        $this->where($index . ' IN(' . implode(',', $ids) . ')', null, false);
+
+        return 'UPDATE ' . $this->compileIgnore('update') . ' ' . $this->getFullName($table) . ' SET ' . substr($cases, 0, -2) . $this->compileWhereHaving('QBWhere');
+    }
+
+    /**
+     * Increments a numeric column by the specified value.
+     *
+     * @return bool
+     */
+    public function increment(string $column, int $value = 1)
+    {
+        $column = $this->db->protectIdentifiers($column);
+
+        if ($this->castTextToInt) {
+            $values = [$column => "CONVERT(VARCHAR(MAX),CONVERT(INT,CONVERT(VARCHAR(MAX), {$column})) + {$value})"];
+        } else {
+            $values = [$column => "{$column} + {$value}"];
+        }
+
+        $sql = $this->_update($this->QBFrom[0], $values);
+
+        return $this->db->query($sql, $this->binds, false);
+    }
+
+    /**
+     * Decrements a numeric column by the specified value.
+     *
+     * @return bool
+     */
+    public function decrement(string $column, int $value = 1)
+    {
+        $column = $this->db->protectIdentifiers($column);
+
+        if ($this->castTextToInt) {
+            $values = [$column => "CONVERT(VARCHAR(MAX),CONVERT(INT,CONVERT(VARCHAR(MAX), {$column})) - {$value})"];
+        } else {
+            $values = [$column => "{$column} + {$value}"];
+        }
+
+        $sql = $this->_update($this->QBFrom[0], $values);
+
+        return $this->db->query($sql, $this->binds, false);
+    }
+
+    /**
+     * Get full name of the table
+     */
+    private function getFullName(string $table): string
+    {
+        $alias = '';
+
+        if (strpos($table, ' ') !== false) {
+            $alias = explode(' ', $table);
+            $table = array_shift($alias);
+            $alias = ' ' . implode(' ', $alias);
+        }
+
+        if ($this->db->escapeChar === '"') {
+            return '"' . $this->db->getDatabase() . '"."' . $this->db->schema . '"."' . str_replace('"', '', $table) . '"' . $alias;
+        }
+
+        return '[' . $this->db->getDatabase() . '].[' . $this->db->schema . '].[' . str_replace('"', '', $table) . ']' . str_replace('"', '', $alias);
+    }
+
+    /**
+     * Add permision statements for index value inserts
+     */
+    private function addIdentity(string $fullTable, string $insert): string
+    {
+        return 'SET IDENTITY_INSERT ' . $fullTable . " ON\n" . $insert . "\nSET IDENTITY_INSERT " . $fullTable . ' OFF';
+    }
+
+    /**
+     * Local implementation of limit
+     */
+    protected function _limit(string $sql, bool $offsetIgnore = false): string
+    {
+        if (empty($this->QBOrderBy)) {
+            $sql .= ' ORDER BY (SELECT NULL) ';
+        }
+
+        if ($offsetIgnore) {
+            $sql .= ' OFFSET 0 ';
+        } else {
+            $sql .= is_int($this->QBOffset) ? ' OFFSET ' . $this->QBOffset : ' OFFSET 0 ';
+        }
+
+        return $sql . ' ROWS FETCH NEXT ' . $this->QBLimit . ' ROWS ONLY ';
+    }
+
+    /**
+     * Compiles a replace into string and runs the query
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function replace(?array $set = null)
+    {
+        if ($set !== null) {
+            $this->set($set);
+        }
+
+        if (empty($this->QBSet)) {
+            if (CI_DEBUG) {
+                throw new DatabaseException('You must use the "set" method to update an entry.');
+            }
+
+            return false; // @codeCoverageIgnore
+        }
+
+        $table = $this->QBFrom[0];
+
+        $sql = $this->_replace($table, array_keys($this->QBSet), array_values($this->QBSet));
+
+        $this->resetWrite();
+
+        if ($this->testMode) {
+            return $sql;
+        }
+
+        $this->db->simpleQuery('SET IDENTITY_INSERT ' . $this->getFullName($table) . ' ON');
+
+        $result = $this->db->query($sql, $this->binds, false);
+        $this->db->simpleQuery('SET IDENTITY_INSERT ' . $this->getFullName($table) . ' OFF');
+
+        return $result;
+    }
+
+    /**
+     * Generates a platform-specific replace string from the supplied data
+     * on match delete and insert
+     */
+    protected function _replace(string $table, array $keys, array $values): string
+    {
+        // check whether the existing keys are part of the primary key.
+        // if so then use them for the "ON" part and exclude them from the $values and $keys
+        $pKeys     = $this->db->getIndexData($table);
+        $keyFields = [];
+
+        foreach ($pKeys as $key) {
+            if ($key->type === 'PRIMARY') {
+                $keyFields = array_merge($keyFields, $key->fields);
+            }
+
+            if ($key->type === 'UNIQUE') {
+                $keyFields = array_merge($keyFields, $key->fields);
+            }
+        }
+
+        // Get the unique field names
+        $escKeyFields = array_map(function (string $field): string {
+            return $this->db->protectIdentifiers($field);
+        }, array_values(array_unique($keyFields)));
+
+        // Get the binds
+        $binds = $this->binds;
+        array_walk($binds, static function (&$item) {
+            $item = $item[0];
+        });
+
+        // Get the common field and values from the keys data and index fields
+        $common = array_intersect($keys, $escKeyFields);
+        $bingo  = [];
+
+        foreach ($common as $v) {
+            $k = array_search($v, $keys, true);
+
+            $bingo[$keys[$k]] = $binds[trim($values[$k], ':')];
+        }
+
+        // Querying existing data
+        $builder = $this->db->table($table);
+
+        foreach ($bingo as $k => $v) {
+            $builder->where($k, $v);
+        }
+
+        $q = $builder->get()->getResult();
+
+        // Delete entries if we find them
+        if ($q !== []) {
+            $delete = $this->db->table($table);
+
+            foreach ($bingo as $k => $v) {
+                $delete->where($k, $v);
+            }
+
+            $delete->delete();
+        }
+
+        return sprintf('INSERT INTO %s (%s) VALUES (%s);', $this->getFullName($table), implode(',', $keys), implode(',', $values));
+    }
+
+    /**
+     * SELECT [MAX|MIN|AVG|SUM|COUNT]()
+     *
+     * Handle float return value
+     *
+     * @return BaseBuilder
+     */
+    protected function maxMinAvgSum(string $select = '', string $alias = '', string $type = 'MAX')
+    {
+        // int functions can be handled by parent
+        if ($type !== 'AVG') {
+            return parent::maxMinAvgSum($select, $alias, $type);
+        }
+
+        if ($select === '') {
+            throw DataException::forEmptyInputGiven('Select');
+        }
+
+        if (strpos($select, ',') !== false) {
+            throw DataException::forInvalidArgument('Column name not separated by comma');
+        }
+
+        if ($alias === '') {
+            $alias = $this->createAliasFromTable(trim($select));
+        }
+
+        $sql = $type . '( CAST( ' . $this->db->protectIdentifiers(trim($select)) . ' AS FLOAT ) ) AS ' . $this->db->escapeIdentifiers(trim($alias));
+
+        $this->QBSelect[]   = $sql;
+        $this->QBNoEscape[] = null;
+
+        return $this;
+    }
+
+    /**
+     * "Count All" query
+     *
+     * Generates a platform-specific query string that counts all records in
+     * the particular table
+     *
+     * @param bool $reset Are we want to clear query builder values?
+     *
+     * @return int|string when $test = true
+     */
+    public function countAll(bool $reset = true)
+    {
+        $table = $this->QBFrom[0];
+
+        $sql = $this->countString . $this->db->escapeIdentifiers('numrows') . ' FROM ' . $this->getFullName($table);
+
+        if ($this->testMode) {
+            return $sql;
+        }
+
+        $query = $this->db->query($sql, null, false);
+        if (empty($query->getResult())) {
+            return 0;
+        }
+
+        $query = $query->getRow();
+
+        if ($reset === true) {
+            $this->resetSelect();
+        }
+
+        return (int) $query->numrows;
+    }
+
+    /**
+     * Delete statement
+     */
+    protected function _delete(string $table): string
+    {
+        return 'DELETE' . (empty($this->QBLimit) ? '' : ' TOP (' . $this->QBLimit . ') ') . ' FROM ' . $this->getFullName($table) . $this->compileWhereHaving('QBWhere');
+    }
+
+    /**
+     * Compiles a delete string and runs the query
+     *
+     * @param mixed $where
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function delete($where = '', ?int $limit = null, bool $resetData = true)
+    {
+        $table = $this->db->protectIdentifiers($this->QBFrom[0], true, null, false);
+
+        if ($where !== '') {
+            $this->where($where);
+        }
+
+        if (empty($this->QBWhere)) {
+            if (CI_DEBUG) {
+                throw new DatabaseException('Deletes are not allowed unless they contain a "where" or "like" clause.');
+            }
+
+            return false; // @codeCoverageIgnore
+        }
+
+        if (! empty($limit)) {
+            $this->QBLimit = $limit;
+        }
+
+        $sql = $this->_delete($table);
+
+        if ($resetData) {
+            $this->resetWrite();
+        }
+
+        return $this->testMode ? $sql : $this->db->query($sql, $this->binds, false);
+    }
+
+    /**
+     * Compile the SELECT statement
+     *
+     * Generates a query string based on which functions were used.
+     *
+     * @param bool $selectOverride
+     */
+    protected function compileSelect($selectOverride = false): string
+    {
+        // Write the "select" portion of the query
+        if ($selectOverride !== false) {
+            $sql = $selectOverride;
+        } else {
+            $sql = (! $this->QBDistinct) ? 'SELECT ' : 'SELECT DISTINCT ';
+
+            // SQL Server can't work with select * if group by is specified
+            if (empty($this->QBSelect) && ! empty($this->QBGroupBy) && is_array($this->QBGroupBy)) {
+                foreach ($this->QBGroupBy as $field) {
+                    $this->QBSelect[] = is_array($field) ? $field['field'] : $field;
+                }
+            }
+
+            if (empty($this->QBSelect)) {
+                $sql .= '*';
+            } else {
+                // Cycle through the "select" portion of the query and prep each column name.
+                // The reason we protect identifiers here rather than in the select() function
+                // is because until the user calls the from() function we don't know if there are aliases
+                foreach ($this->QBSelect as $key => $val) {
+                    $noEscape             = $this->QBNoEscape[$key] ?? null;
+                    $this->QBSelect[$key] = $this->db->protectIdentifiers($val, false, $noEscape);
+                }
+
+                $sql .= implode(', ', $this->QBSelect);
+            }
+        }
+
+        // Write the "FROM" portion of the query
+        if (! empty($this->QBFrom)) {
+            $sql .= "\nFROM " . $this->_fromTables();
+        }
+
+        // Write the "JOIN" portion of the query
+        if (! empty($this->QBJoin)) {
+            $sql .= "\n" . implode("\n", $this->QBJoin);
+        }
+
+        $sql .= $this->compileWhereHaving('QBWhere')
+            . $this->compileGroupBy()
+            . $this->compileWhereHaving('QBHaving')
+            . $this->compileOrderBy(); // ORDER BY
+
+        // LIMIT
+        if ($this->QBLimit) {
+            $sql = $this->_limit($sql . "\n");
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Compiles the select statement based on the other functions called
+     * and runs the query
+     *
+     * @return ResultInterface
+     */
+    public function get(?int $limit = null, int $offset = 0, bool $reset = true)
+    {
+        if ($limit !== null) {
+            $this->limit($limit, $offset);
+        }
+
+        $result = $this->testMode ? $this->getCompiledSelect($reset) : $this->db->query($this->compileSelect(), $this->binds, false);
+
+        if ($reset) {
+            $this->resetSelect();
+
+            // Clear our binds so we don't eat up memory
+            $this->binds = [];
+        }
+
+        return $result;
+    }
+}

system/Database/SQLSRV/Connection.php

@@ -0,0 +1,537 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use Exception;
+use stdClass;
+
+/**
+ * Connection for SQLSRV
+ */
+class Connection extends BaseConnection
+{
+    /**
+     * Database driver
+     *
+     * @var string
+     */
+    public $DBDriver = 'SQLSRV';
+
+    /**
+     * Database name
+     *
+     * @var string
+     */
+    public $database;
+
+    /**
+     * Scrollable flag
+     *
+     * Determines what cursor type to use when executing queries.
+     *
+     * FALSE or SQLSRV_CURSOR_FORWARD would increase performance,
+     * but would disable num_rows() (and possibly insert_id())
+     *
+     * @var mixed
+     */
+    public $scrollable;
+
+    /**
+     * Identifier escape character
+     *
+     * @var string
+     */
+    public $escapeChar = '"';
+
+    /**
+     * Database schema
+     *
+     * @var string
+     */
+    public $schema = 'dbo';
+
+    /**
+     * Quoted identifier flag
+     *
+     * Whether to use SQL-92 standard quoted identifier
+     * (double quotes) or brackets for identifier escaping.
+     *
+     * @var bool
+     */
+    protected $_quoted_identifier = true;
+
+    /**
+     * List of reserved identifiers
+     *
+     * Identifiers that must NOT be escaped.
+     *
+     * @var string[]
+     */
+    protected $_reserved_identifiers = ['*'];
+
+    /**
+     * Class constructor
+     */
+    public function __construct(array $params)
+    {
+        parent::__construct($params);
+
+        // This is only supported as of SQLSRV 3.0
+        if ($this->scrollable === null) {
+            $this->scrollable = defined('SQLSRV_CURSOR_CLIENT_BUFFERED') ? SQLSRV_CURSOR_CLIENT_BUFFERED : false;
+        }
+    }
+
+    /**
+     * Connect to the database.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function connect(bool $persistent = false)
+    {
+        $charset = in_array(strtolower($this->charset), ['utf-8', 'utf8'], true) ? 'UTF-8' : SQLSRV_ENC_CHAR;
+
+        $connection = [
+            'UID'                  => empty($this->username) ? '' : $this->username,
+            'PWD'                  => empty($this->password) ? '' : $this->password,
+            'Database'             => $this->database,
+            'ConnectionPooling'    => $persistent ? 1 : 0,
+            'CharacterSet'         => $charset,
+            'Encrypt'              => $this->encrypt === true ? 1 : 0,
+            'ReturnDatesAsStrings' => 1,
+        ];
+
+        // If the username and password are both empty, assume this is a
+        // 'Windows Authentication Mode' connection.
+        if (empty($connection['UID']) && empty($connection['PWD'])) {
+            unset($connection['UID'], $connection['PWD']);
+        }
+
+        sqlsrv_configure('WarningsReturnAsErrors', 0);
+        $this->connID = sqlsrv_connect($this->hostname, $connection);
+
+        if ($this->connID !== false) {
+            // Determine how identifiers are escaped
+            $query = $this->query('SELECT CASE WHEN (@@OPTIONS | 256) = @@OPTIONS THEN 1 ELSE 0 END AS qi');
+            $query = $query->getResultObject();
+
+            $this->_quoted_identifier = empty($query) ? false : (bool) $query[0]->qi;
+            $this->escapeChar         = ($this->_quoted_identifier) ? '"' : ['[', ']'];
+
+            return $this->connID;
+        }
+
+        $errors = [];
+
+        foreach (sqlsrv_errors(SQLSRV_ERR_ERRORS) as $error) {
+            $errors[] = preg_replace('/(\[.+\]\[.+\](?:\[.+\])?)(.+)/', '$2', $error['message']);
+        }
+
+        throw new DatabaseException(implode("\n", $errors));
+    }
+
+    /**
+     * Keep or establish the connection if no queries have been sent for
+     * a length of time exceeding the server's idle timeout.
+     */
+    public function reconnect()
+    {
+        $this->close();
+        $this->initialize();
+    }
+
+    /**
+     * Close the database connection.
+     */
+    protected function _close()
+    {
+        sqlsrv_close($this->connID);
+    }
+
+    /**
+     * Platform-dependant string escape
+     */
+    protected function _escapeString(string $str): string
+    {
+        return str_replace("'", "''", remove_invisible_characters($str, false));
+    }
+
+    /**
+     * Insert ID
+     */
+    public function insertID(): int
+    {
+        return $this->query('SELECT SCOPE_IDENTITY() AS insert_id')->getRow()->insert_id ?? 0;
+    }
+
+    /**
+     * Generates the SQL for listing tables in a platform-dependent manner.
+     */
+    protected function _listTables(bool $prefixLimit = false): string
+    {
+        $sql = 'SELECT [TABLE_NAME] AS "name"'
+            . ' FROM [INFORMATION_SCHEMA].[TABLES] '
+            . ' WHERE '
+            . " [TABLE_SCHEMA] = '" . $this->schema . "'    ";
+
+        if ($prefixLimit === true && $this->DBPrefix !== '') {
+            $sql .= " AND [TABLE_NAME] LIKE '" . $this->escapeLikeString($this->DBPrefix) . "%' "
+                . sprintf($this->likeEscapeStr, $this->likeEscapeChar);
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Generates a platform-specific query string so that the column names can be fetched.
+     */
+    protected function _listColumns(string $table = ''): string
+    {
+        return 'SELECT [COLUMN_NAME] '
+            . ' FROM [INFORMATION_SCHEMA].[COLUMNS]'
+            . ' WHERE  [TABLE_NAME] = ' . $this->escape($this->DBPrefix . $table)
+            . ' AND [TABLE_SCHEMA] = ' . $this->escape($this->schema);
+    }
+
+    /**
+     * Returns an array of objects with index data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _indexData(string $table): array
+    {
+        $sql = 'EXEC sp_helpindex ' . $this->escape($this->schema . '.' . $table);
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetIndexData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj       = new stdClass();
+            $obj->name = $row->index_name;
+
+            $_fields     = explode(',', trim($row->index_keys));
+            $obj->fields = array_map(static function ($v) {
+                return trim($v);
+            }, $_fields);
+
+            if (strpos($row->index_description, 'primary key located on') !== false) {
+                $obj->type = 'PRIMARY';
+            } else {
+                $obj->type = (strpos($row->index_description, 'nonclustered, unique') !== false) ? 'UNIQUE' : 'INDEX';
+            }
+
+            $retVal[$obj->name] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with Foreign key data
+     * referenced_object_id  parent_object_id
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _foreignKeyData(string $table): array
+    {
+        $sql = 'SELECT '
+            . 'f.name as constraint_name, '
+            . 'OBJECT_NAME (f.parent_object_id) as table_name, '
+            . 'COL_NAME(fc.parent_object_id,fc.parent_column_id) column_name, '
+            . 'OBJECT_NAME(f.referenced_object_id) foreign_table_name, '
+            . 'COL_NAME(fc.referenced_object_id,fc.referenced_column_id) foreign_column_name '
+            . 'FROM  '
+            . 'sys.foreign_keys AS f '
+            . 'INNER JOIN  '
+            . 'sys.foreign_key_columns AS fc  '
+            . 'ON f.OBJECT_ID = fc.constraint_object_id '
+            . 'INNER JOIN  '
+            . 'sys.tables t  '
+            . 'ON t.OBJECT_ID = fc.referenced_object_id '
+            . 'WHERE  '
+            . 'OBJECT_NAME (f.parent_object_id) = ' . $this->escape($table);
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetForeignKeyData'));
+        }
+
+        $query  = $query->getResultObject();
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj = new stdClass();
+
+            $obj->constraint_name     = $row->constraint_name;
+            $obj->table_name          = $row->table_name;
+            $obj->column_name         = $row->column_name;
+            $obj->foreign_table_name  = $row->foreign_table_name;
+            $obj->foreign_column_name = $row->foreign_column_name;
+
+            $retVal[] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Disables foreign key checks temporarily.
+     *
+     * @return string
+     */
+    protected function _disableForeignKeyChecks()
+    {
+        return 'EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT ALL"';
+    }
+
+    /**
+     * Enables foreign key checks temporarily.
+     *
+     * @return string
+     */
+    protected function _enableForeignKeyChecks()
+    {
+        return 'EXEC sp_MSforeachtable "ALTER TABLE ? WITH CHECK CHECK CONSTRAINT ALL"';
+    }
+
+    /**
+     * Returns an array of objects with field data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _fieldData(string $table): array
+    {
+        $sql = 'SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, COLUMN_DEFAULT
+			FROM INFORMATION_SCHEMA.COLUMNS
+			WHERE TABLE_NAME= ' . $this->escape(($table));
+
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetFieldData'));
+        }
+
+        $query  = $query->getResultObject();
+        $retVal = [];
+
+        for ($i = 0, $c = count($query); $i < $c; $i++) {
+            $retVal[$i] = new stdClass();
+
+            $retVal[$i]->name    = $query[$i]->COLUMN_NAME;
+            $retVal[$i]->type    = $query[$i]->DATA_TYPE;
+            $retVal[$i]->default = $query[$i]->COLUMN_DEFAULT;
+
+            $retVal[$i]->max_length = $query[$i]->CHARACTER_MAXIMUM_LENGTH > 0
+                ? $query[$i]->CHARACTER_MAXIMUM_LENGTH
+                : $query[$i]->NUMERIC_PRECISION;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Begin Transaction
+     */
+    protected function _transBegin(): bool
+    {
+        return sqlsrv_begin_transaction($this->connID);
+    }
+
+    /**
+     * Commit Transaction
+     */
+    protected function _transCommit(): bool
+    {
+        return sqlsrv_commit($this->connID);
+    }
+
+    /**
+     * Rollback Transaction
+     */
+    protected function _transRollback(): bool
+    {
+        return sqlsrv_rollback($this->connID);
+    }
+
+    /**
+     * Returns the last error code and message.
+     * Must return this format: ['code' => string|int, 'message' => string]
+     * intval(code) === 0 means "no error".
+     *
+     * @return array<string, int|string>
+     */
+    public function error(): array
+    {
+        $error = [
+            'code'    => '00000',
+            'message' => '',
+        ];
+
+        $sqlsrvErrors = sqlsrv_errors(SQLSRV_ERR_ERRORS);
+
+        if (! is_array($sqlsrvErrors)) {
+            return $error;
+        }
+
+        $sqlsrvError = array_shift($sqlsrvErrors);
+        if (isset($sqlsrvError['SQLSTATE'])) {
+            $error['code'] = isset($sqlsrvError['code']) ? $sqlsrvError['SQLSTATE'] . '/' . $sqlsrvError['code'] : $sqlsrvError['SQLSTATE'];
+        } elseif (isset($sqlsrvError['code'])) {
+            $error['code'] = $sqlsrvError['code'];
+        }
+
+        if (isset($sqlsrvError['message'])) {
+            $error['message'] = $sqlsrvError['message'];
+        }
+
+        return $error;
+    }
+
+    /**
+     * Returns the total number of rows affected by this query.
+     */
+    public function affectedRows(): int
+    {
+        return sqlsrv_rows_affected($this->resultID);
+    }
+
+    /**
+     * Select a specific database table to use.
+     *
+     * @return mixed
+     */
+    public function setDatabase(?string $databaseName = null)
+    {
+        if (empty($databaseName)) {
+            $databaseName = $this->database;
+        }
+
+        if (empty($this->connID)) {
+            $this->initialize();
+        }
+
+        if ($this->execute('USE ' . $this->_escapeString($databaseName))) {
+            $this->database  = $databaseName;
+            $this->dataCache = [];
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Executes the query against the database.
+     *
+     * @return mixed
+     */
+    protected function execute(string $sql)
+    {
+        $stmt = ($this->scrollable === false || $this->isWriteType($sql)) ?
+            sqlsrv_query($this->connID, $sql) :
+            sqlsrv_query($this->connID, $sql, [], ['Scrollable' => $this->scrollable]);
+
+        if ($stmt === false) {
+            $error = $this->error();
+
+            log_message('error', $error['message']);
+            if ($this->DBDebug) {
+                throw new Exception($error['message']);
+            }
+        }
+
+        return $stmt;
+    }
+
+    /**
+     * Returns the last error encountered by this connection.
+     *
+     * @return mixed
+     */
+    public function getError()
+    {
+        $error = [
+            'code'    => '00000',
+            'message' => '',
+        ];
+
+        $sqlsrvErrors = sqlsrv_errors(SQLSRV_ERR_ERRORS);
+
+        if (! is_array($sqlsrvErrors)) {
+            return $error;
+        }
+
+        $sqlsrvError = array_shift($sqlsrvErrors);
+        if (isset($sqlsrvError['SQLSTATE'])) {
+            $error['code'] = isset($sqlsrvError['code']) ? $sqlsrvError['SQLSTATE'] . '/' . $sqlsrvError['code'] : $sqlsrvError['SQLSTATE'];
+        } elseif (isset($sqlsrvError['code'])) {
+            $error['code'] = $sqlsrvError['code'];
+        }
+
+        if (isset($sqlsrvError['message'])) {
+            $error['message'] = $sqlsrvError['message'];
+        }
+
+        return $error;
+    }
+
+    /**
+     * The name of the platform in use (MySQLi, mssql, etc)
+     */
+    public function getPlatform(): string
+    {
+        return $this->DBDriver;
+    }
+
+    /**
+     * Returns a string containing the version of the database being used.
+     */
+    public function getVersion(): string
+    {
+        if (isset($this->dataCache['version'])) {
+            return $this->dataCache['version'];
+        }
+
+        if (! $this->connID || empty($info = sqlsrv_server_info($this->connID))) {
+            $this->initialize();
+        }
+
+        return isset($info['SQLServerVersion']) ? $this->dataCache['version'] = $info['SQLServerVersion'] : false;
+    }
+
+    /**
+     * Determines if a query is a "write" type.
+     *
+     * Overrides BaseConnection::isWriteType, adding additional read query types.
+     *
+     * @param mixed $sql
+     */
+    public function isWriteType($sql): bool
+    {
+        if (preg_match('/^\s*"?(EXEC\s*sp_rename)\s/i', $sql)) {
+            return true;
+        }
+
+        return parent::isWriteType($sql);
+    }
+}

system/Database/SQLSRV/Forge.php

@@ -0,0 +1,405 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Forge as BaseForge;
+
+/**
+ * Forge for SQLSRV
+ */
+class Forge extends BaseForge
+{
+    /**
+     * DROP CONSTRAINT statement
+     *
+     * @var string
+     */
+    protected $dropConstraintStr;
+
+    /**
+     * DROP INDEX statement
+     *
+     * @var string
+     */
+    protected $dropIndexStr;
+
+    /**
+     * CREATE DATABASE IF statement
+     *
+     * @todo missing charset, collat & check for existent
+     *
+     * @var string
+     */
+    protected $createDatabaseIfStr = "DECLARE @DBName VARCHAR(255) = '%s'\nDECLARE @SQL VARCHAR(max) = 'IF DB_ID( ''' + @DBName + ''' ) IS NULL CREATE DATABASE ' + @DBName\nEXEC( @SQL )";
+
+    /**
+     * CREATE DATABASE IF statement
+     *
+     * @todo missing charset & collat
+     *
+     * @var string
+     */
+    protected $createDatabaseStr = 'CREATE DATABASE %s ';
+
+    /**
+     * CHECK DATABASE EXIST statement
+     *
+     * @var string
+     */
+    protected $checkDatabaseExistStr = 'IF DB_ID( %s ) IS NOT NULL SELECT 1';
+
+    /**
+     * RENAME TABLE statement
+     *
+     * While the below statement would work, it returns an error.
+     * Also MS recommends dropping and dropping and re-creating the table.
+     *
+     * @see https://docs.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-rename-transact-sql?view=sql-server-2017
+     * 'EXEC sp_rename %s , %s ;'
+     *
+     * @var string
+     */
+    protected $renameTableStr;
+
+    /**
+     * UNSIGNED support
+     *
+     * @var array
+     */
+    protected $unsigned = [
+        'TINYINT'  => 'SMALLINT',
+        'SMALLINT' => 'INT',
+        'INT'      => 'BIGINT',
+        'REAL'     => 'FLOAT',
+    ];
+
+    /**
+     * CREATE TABLE IF statement
+     *
+     * @var string
+     */
+    protected $createTableIfStr;
+
+    /**
+     * CREATE TABLE statement
+     *
+     * @var string
+     */
+    protected $createTableStr;
+
+    public function __construct(BaseConnection $db)
+    {
+        parent::__construct($db);
+
+        $this->createTableIfStr = 'IF NOT EXISTS'
+            . '(SELECT t.name, s.name as schema_name, t.type_desc '
+            . 'FROM sys.tables t '
+            . 'INNER JOIN sys.schemas s on s.schema_id = t.schema_id '
+            . "WHERE s.name=N'" . $this->db->schema . "' "
+            . "AND t.name=REPLACE(N'%s', '\"', '') "
+            . "AND t.type_desc='USER_TABLE')\nCREATE TABLE ";
+
+        $this->createTableStr = '%s ' . $this->db->escapeIdentifiers($this->db->schema) . ".%s (%s\n) ";
+        $this->renameTableStr = 'EXEC sp_rename [' . $this->db->escapeIdentifiers($this->db->schema) . '.%s] , %s ;';
+
+        $this->dropConstraintStr = 'ALTER TABLE ' . $this->db->escapeIdentifiers($this->db->schema) . '.%s DROP CONSTRAINT %s';
+        $this->dropIndexStr      = 'DROP INDEX %s ON ' . $this->db->escapeIdentifiers($this->db->schema) . '.%s';
+    }
+
+    /**
+     * CREATE TABLE attributes
+     */
+    protected function _createTableAttributes(array $attributes): string
+    {
+        return '';
+    }
+
+    /**
+     * @param mixed $field
+     *
+     * @return false|string|string[]
+     */
+    protected function _alterTable(string $alterType, string $table, $field)
+    {
+
+        // Handle DROP here
+        if ($alterType === 'DROP') {
+            // check if fields are part of any indexes
+            $indexData = $this->db->getIndexData($table);
+
+            foreach ($indexData as $index) {
+                if (is_string($field)) {
+                    $field = explode(',', $field);
+                }
+
+                $fld = array_intersect($field, $index->fields);
+
+                // Drop index if field is part of an index
+                if (! empty($fld)) {
+                    $this->_dropIndex($table, $index);
+                }
+            }
+
+            $sql = 'ALTER TABLE ' . $this->db->escapeIdentifiers($this->db->schema) . '.' . $this->db->escapeIdentifiers($table) . ' DROP ';
+
+            $fields = array_map(static function ($item) {
+                return 'COLUMN [' . trim($item) . ']';
+            }, (array) $field);
+
+            return $sql . implode(',', $fields);
+        }
+
+        $sql = 'ALTER TABLE ' . $this->db->escapeIdentifiers($this->db->schema) . '.' . $this->db->escapeIdentifiers($table);
+        $sql .= ($alterType === 'ADD') ? 'ADD ' : ' ';
+
+        $sqls = [];
+
+        if ($alterType === 'ADD') {
+            foreach ($field as $data) {
+                $sqls[] = $sql . ($data['_literal'] !== false ? $data['_literal'] : $this->_processColumn($data));
+            }
+
+            return $sqls;
+        }
+
+        foreach ($field as $data) {
+            if ($data['_literal'] !== false) {
+                return false;
+            }
+
+            if (isset($data['type'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . " {$data['type']}{$data['length']}";
+            }
+
+            if (! empty($data['default'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ADD CONSTRAINT ' . $this->db->escapeIdentifiers($data['name']) . '_def'
+                    . " DEFAULT {$data['default']} FOR " . $this->db->escapeIdentifiers($data['name']);
+            }
+
+            if (isset($data['null'])) {
+                $sqls[] = $sql . ' ALTER COLUMN ' . $this->db->escapeIdentifiers($data['name'])
+                    . ($data['null'] === true ? ' DROP' : '') . " {$data['type']}{$data['length']} NOT NULL";
+            }
+
+            if (! empty($data['comment'])) {
+                $sqls[] = 'EXEC sys.sp_addextendedproperty '
+                    . "@name=N'Caption', @value=N'" . $data['comment'] . "' , "
+                    . "@level0type=N'SCHEMA',@level0name=N'" . $this->db->schema . "', "
+                    . "@level1type=N'TABLE',@level1name=N'" . $this->db->escapeIdentifiers($table) . "', "
+                    . "@level2type=N'COLUMN',@level2name=N'" . $this->db->escapeIdentifiers($data['name']) . "'";
+            }
+
+            if (! empty($data['new_name'])) {
+                $sqls[] = "EXEC sp_rename  '[" . $this->db->schema . '].[' . $table . '].[' . $data['name'] . "]' , '" . $data['new_name'] . "', 'COLUMN';";
+            }
+        }
+
+        return $sqls;
+    }
+
+    /**
+     * Drop index for table
+     *
+     * @return mixed
+     */
+    protected function _dropIndex(string $table, object $indexData)
+    {
+        if ($indexData->type === 'PRIMARY') {
+            $sql = 'ALTER TABLE [' . $this->db->schema . '].[' . $table . '] DROP [' . $indexData->name . ']';
+        } else {
+            $sql = 'DROP INDEX [' . $indexData->name . '] ON [' . $this->db->schema . '].[' . $table . ']';
+        }
+
+        return $this->db->simpleQuery($sql);
+    }
+
+    /**
+     * Process indexes
+     *
+     * @return array|string
+     */
+    protected function _processIndexes(string $table)
+    {
+        $sqls = [];
+
+        for ($i = 0, $c = count($this->keys); $i < $c; $i++) {
+            $this->keys[$i] = (array) $this->keys[$i];
+
+            for ($i2 = 0, $c2 = count($this->keys[$i]); $i2 < $c2; $i2++) {
+                if (! isset($this->fields[$this->keys[$i][$i2]])) {
+                    unset($this->keys[$i][$i2]);
+                }
+            }
+
+            if (count($this->keys[$i]) <= 0) {
+                continue;
+            }
+
+            if (in_array($i, $this->uniqueKeys, true)) {
+                $sqls[] = 'ALTER TABLE '
+                    . $this->db->escapeIdentifiers($this->db->schema) . '.' . $this->db->escapeIdentifiers($table)
+                    . ' ADD CONSTRAINT ' . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
+                    . ' UNIQUE (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';
+
+                continue;
+            }
+
+            $sqls[] = 'CREATE INDEX '
+                . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
+                . ' ON ' . $this->db->escapeIdentifiers($this->db->schema) . '.' . $this->db->escapeIdentifiers($table)
+                . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';
+        }
+
+        return $sqls;
+    }
+
+    /**
+     * Process column
+     */
+    protected function _processColumn(array $field): string
+    {
+        return $this->db->escapeIdentifiers($field['name'])
+            . (empty($field['new_name']) ? '' : ' ' . $this->db->escapeIdentifiers($field['new_name']))
+            . ' ' . $field['type'] . $field['length']
+            . $field['default']
+            . $field['null']
+            . $field['auto_increment']
+            . ''
+            . $field['unique'];
+    }
+
+    /**
+     * Process foreign keys
+     *
+     * @param string $table Table name
+     */
+    protected function _processForeignKeys(string $table): string
+    {
+        $sql = '';
+
+        $allowActions = ['CASCADE', 'SET NULL', 'NO ACTION', 'RESTRICT', 'SET DEFAULT'];
+
+        foreach ($this->foreignKeys as $fkey) {
+            $nameIndex            = $table . '_' . implode('_', $fkey['field']) . '_foreign';
+            $nameIndexFilled      = $this->db->escapeIdentifiers($nameIndex);
+            $foreignKeyFilled     = implode(', ', $this->db->escapeIdentifiers($fkey['field']));
+            $referenceTableFilled = $this->db->escapeIdentifiers($this->db->DBPrefix . $fkey['referenceTable']);
+            $referenceFieldFilled = implode(', ', $this->db->escapeIdentifiers($fkey['referenceField']));
+
+            $formatSql = ",\n\tCONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s(%s)";
+            $sql .= sprintf($formatSql, $nameIndexFilled, $foreignKeyFilled, $referenceTableFilled, $referenceFieldFilled);
+
+            if ($fkey['onDelete'] !== false && in_array($fkey['onDelete'], $allowActions, true)) {
+                $sql .= ' ON DELETE ' . $fkey['onDelete'];
+            }
+
+            if ($fkey['onUpdate'] !== false && in_array($fkey['onUpdate'], $allowActions, true)) {
+                $sql .= ' ON UPDATE ' . $fkey['onUpdate'];
+            }
+        }
+
+        return $sql;
+    }
+
+    /**
+     * Process primary keys
+     */
+    protected function _processPrimaryKeys(string $table): string
+    {
+        for ($i = 0, $c = count($this->primaryKeys); $i < $c; $i++) {
+            if (! isset($this->fields[$this->primaryKeys[$i]])) {
+                unset($this->primaryKeys[$i]);
+            }
+        }
+
+        if ($this->primaryKeys !== []) {
+            $sql = ",\n\tCONSTRAINT " . $this->db->escapeIdentifiers('pk_' . $table)
+                . ' PRIMARY KEY(' . implode(', ', $this->db->escapeIdentifiers($this->primaryKeys)) . ')';
+        }
+
+        return $sql ?? '';
+    }
+
+    /**
+     * Performs a data type mapping between different databases.
+     */
+    protected function _attributeType(array &$attributes)
+    {
+        // Reset field lengths for data types that don't support it
+        if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== false) {
+            $attributes['CONSTRAINT'] = null;
+        }
+
+        switch (strtoupper($attributes['TYPE'])) {
+            case 'MEDIUMINT':
+                $attributes['TYPE']     = 'INTEGER';
+                $attributes['UNSIGNED'] = false;
+                break;
+
+            case 'INTEGER':
+                $attributes['TYPE'] = 'INT';
+                break;
+
+            case 'ENUM':
+                $attributes['TYPE']       = 'TEXT';
+                $attributes['CONSTRAINT'] = null;
+                break;
+
+            case 'TIMESTAMP':
+                $attributes['TYPE'] = 'DATETIME';
+                break;
+
+            case 'BOOLEAN':
+                $attributes['TYPE'] = 'BIT';
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Field attribute AUTO_INCREMENT
+     */
+    protected function _attributeAutoIncrement(array &$attributes, array &$field)
+    {
+        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true && stripos($field['type'], 'INT') !== false) {
+            $field['auto_increment'] = ' IDENTITY(1,1)';
+        }
+    }
+
+    /**
+     * Generates a platform-specific DROP TABLE string
+     *
+     * @todo Support for cascade
+     */
+    protected function _dropTable(string $table, bool $ifExists, bool $cascade): string
+    {
+        $sql = 'DROP TABLE';
+
+        if ($ifExists) {
+            $sql .= ' IF EXISTS ';
+        }
+
+        $table = ' [' . $this->db->database . '].[' . $this->db->schema . '].[' . $table . '] ';
+
+        $sql .= $table;
+
+        if ($cascade) {
+            $sql .= '';
+        }
+
+        return $sql;
+    }
+}

system/Database/SQLSRV/PreparedQuery.php

@@ -0,0 +1,114 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use BadMethodCallException;
+use CodeIgniter\Database\BasePreparedQuery;
+use Exception;
+
+/**
+ * Prepared query for Postgre
+ */
+class PreparedQuery extends BasePreparedQuery
+{
+    /**
+     * Parameters array used to store the dynamic variables.
+     *
+     * @var array
+     */
+    protected $parameters = [];
+
+    /**
+     * The result boolean from a sqlsrv_execute.
+     *
+     * @var bool
+     */
+    protected $result;
+
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * NOTE: This version is based on SQL code. Child classes should
+     * override this method.
+     *
+     * @param array $options Options takes an associative array;
+     *
+     * @throws Exception
+     *
+     * @return mixed
+     */
+    public function _prepare(string $sql, array $options = [])
+    {
+        // Prepare parameters for the query
+        $queryString = $this->getQueryString();
+
+        $parameters = $this->parameterize($queryString);
+
+        // Prepare the query
+        $this->statement = sqlsrv_prepare($this->db->connID, $sql, $parameters);
+
+        if (! $this->statement) {
+            $info              = $this->db->error();
+            $this->errorCode   = $info['code'];
+            $this->errorString = $info['message'];
+        }
+
+        return $this;
+    }
+
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     */
+    public function _execute(array $data): bool
+    {
+        if (! isset($this->statement)) {
+            throw new BadMethodCallException('You must call prepare before trying to execute a prepared statement.');
+        }
+
+        foreach ($data as $key => $value) {
+            $this->parameters[$key] = $value;
+        }
+
+        $this->result = sqlsrv_execute($this->statement);
+
+        return (bool) $this->result;
+    }
+
+    /**
+     * Returns the result object for the prepared query.
+     *
+     * @return mixed
+     */
+    public function _getResult()
+    {
+        return $this->result;
+    }
+
+    /**
+     * Handle parameters
+     */
+    protected function parameterize(string $queryString): array
+    {
+        $numberOfVariables = substr_count($queryString, '?');
+
+        $params = [];
+
+        for ($c = 0; $c < $numberOfVariables; $c++) {
+            $this->parameters[$c] = null;
+            $params[]             = &$this->parameters[$c];
+        }
+
+        return $params;
+    }
+}

system/Database/SQLSRV/Result.php

@@ -0,0 +1,170 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use CodeIgniter\Database\BaseResult;
+use CodeIgniter\Entity\Entity;
+use stdClass;
+
+/**
+ * Result for SQLSRV
+ */
+class Result extends BaseResult
+{
+    /**
+     * Gets the number of fields in the result set.
+     */
+    public function getFieldCount(): int
+    {
+        return @sqlsrv_num_fields($this->resultID);
+    }
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    public function getFieldNames(): array
+    {
+        $fieldNames = [];
+
+        foreach (sqlsrv_field_metadata($this->resultID) as $field) {
+            $fieldNames[] = $field['Name'];
+        }
+
+        return $fieldNames;
+    }
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    public function getFieldData(): array
+    {
+        static $dataTypes = [
+            SQLSRV_SQLTYPE_BIGINT => 'bigint',
+            SQLSRV_SQLTYPE_BIT    => 'bit',
+            SQLSRV_SQLTYPE_CHAR   => 'char',
+
+            SQLSRV_SQLTYPE_DATE           => 'date',
+            SQLSRV_SQLTYPE_DATETIME       => 'datetime',
+            SQLSRV_SQLTYPE_DATETIME2      => 'datetime2',
+            SQLSRV_SQLTYPE_DATETIMEOFFSET => 'datetimeoffset',
+
+            SQLSRV_SQLTYPE_DECIMAL => 'decimal',
+            SQLSRV_SQLTYPE_FLOAT   => 'float',
+
+            SQLSRV_SQLTYPE_IMAGE   => 'image',
+            SQLSRV_SQLTYPE_INT     => 'int',
+            SQLSRV_SQLTYPE_MONEY   => 'money',
+            SQLSRV_SQLTYPE_NCHAR   => 'nchar',
+            SQLSRV_SQLTYPE_NUMERIC => 'numeric',
+
+            SQLSRV_SQLTYPE_NVARCHAR => 'nvarchar',
+            SQLSRV_SQLTYPE_NTEXT    => 'ntext',
+
+            SQLSRV_SQLTYPE_REAL          => 'real',
+            SQLSRV_SQLTYPE_SMALLDATETIME => 'smalldatetime',
+            SQLSRV_SQLTYPE_SMALLINT      => 'smallint',
+            SQLSRV_SQLTYPE_SMALLMONEY    => 'smallmoney',
+            SQLSRV_SQLTYPE_TEXT          => 'text',
+
+            SQLSRV_SQLTYPE_TIME             => 'time',
+            SQLSRV_SQLTYPE_TIMESTAMP        => 'timestamp',
+            SQLSRV_SQLTYPE_TINYINT          => 'tinyint',
+            SQLSRV_SQLTYPE_UNIQUEIDENTIFIER => 'uniqueidentifier',
+            SQLSRV_SQLTYPE_UDT              => 'udt',
+            SQLSRV_SQLTYPE_VARBINARY        => 'varbinary',
+            SQLSRV_SQLTYPE_VARCHAR          => 'varchar',
+            SQLSRV_SQLTYPE_XML              => 'xml',
+        ];
+
+        $retVal = [];
+
+        foreach (sqlsrv_field_metadata($this->resultID) as $i => $field) {
+            $retVal[$i] = new stdClass();
+
+            $retVal[$i]->name       = $field['Name'];
+            $retVal[$i]->type       = $field['Type'];
+            $retVal[$i]->type_name  = $dataTypes[$field['Type']] ?? null;
+            $retVal[$i]->max_length = $field['Size'];
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Frees the current result.
+     */
+    public function freeResult()
+    {
+        if (is_resource($this->resultID)) {
+            sqlsrv_free_stmt($this->resultID);
+            $this->resultID = false;
+        }
+    }
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @return mixed
+     */
+    public function dataSeek(int $n = 0)
+    {
+        if ($n > 0) {
+            for ($i = 0; $i < $n; $i++) {
+                if (sqlsrv_fetch($this->resultID) === false) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Returns the result set as an array.
+     *
+     * Overridden by driver classes.
+     *
+     * @return mixed
+     */
+    protected function fetchAssoc()
+    {
+        return sqlsrv_fetch_array($this->resultID, SQLSRV_FETCH_ASSOC);
+    }
+
+    /**
+     * Returns the result set as an object.
+     *
+     * @return bool|Entity|object
+     */
+    protected function fetchObject(string $className = 'stdClass')
+    {
+        if (is_subclass_of($className, Entity::class)) {
+            return empty($data = $this->fetchAssoc()) ? false : (new $className())->setAttributes($data);
+        }
+
+        return sqlsrv_fetch_object($this->resultID, $className);
+    }
+
+    /**
+     * Returns the number of rows in the resultID (i.e., SQLSRV query result resource)
+     */
+    public function getNumRows(): int
+    {
+        if (! is_int($this->numRows)) {
+            $this->numRows = sqlsrv_num_rows($this->resultID);
+        }
+
+        return $this->numRows;
+    }
+}

system/Database/SQLSRV/Utils.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLSRV;
+
+use CodeIgniter\Database\BaseUtils;
+use CodeIgniter\Database\ConnectionInterface;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Utils for SQLSRV
+ */
+class Utils extends BaseUtils
+{
+    /**
+     * List databases statement
+     *
+     * @var string
+     */
+    protected $listDatabases = 'EXEC sp_helpdb'; // Can also be: EXEC sp_databases
+
+    /**
+     * OPTIMIZE TABLE statement
+     *
+     * @var string
+     */
+    protected $optimizeTable = 'ALTER INDEX all ON %s REORGANIZE';
+
+    public function __construct(ConnectionInterface &$db)
+    {
+        parent::__construct($db);
+
+        $this->optimizeTable = 'ALTER INDEX all ON  ' . $this->db->schema . '.%s REORGANIZE';
+    }
+
+    /**
+     * Platform dependent version of the backup function.
+     *
+     * @return mixed
+     */
+    public function _backup(?array $prefs = null)
+    {
+        throw new DatabaseException('Unsupported feature of the database platform you are using.');
+    }
+}

system/Database/SQLite3/Builder.php

@@ -0,0 +1,73 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use CodeIgniter\Database\BaseBuilder;
+
+/**
+ * Builder for SQLite3
+ */
+class Builder extends BaseBuilder
+{
+    /**
+     * Default installs of SQLite typically do not
+     * support limiting delete clauses.
+     *
+     * @var bool
+     */
+    protected $canLimitDeletes = false;
+
+    /**
+     * Default installs of SQLite do no support
+     * limiting update queries in combo with WHERE.
+     *
+     * @var bool
+     */
+    protected $canLimitWhereUpdates = false;
+
+    /**
+     * ORDER BY random keyword
+     *
+     * @var array
+     */
+    protected $randomKeyword = [
+        'RANDOM()',
+    ];
+
+    /**
+     * @var array
+     */
+    protected $supportedIgnoreStatements = [
+        'insert' => 'OR IGNORE',
+    ];
+
+    /**
+     * Replace statement
+     *
+     * Generates a platform-specific replace string from the supplied data
+     */
+    protected function _replace(string $table, array $keys, array $values): string
+    {
+        return 'INSERT OR ' . parent::_replace($table, $keys, $values);
+    }
+
+    /**
+     * Generates a platform-specific truncate string from the supplied data
+     *
+     * If the database does not support the TRUNCATE statement,
+     * then this method maps to 'DELETE FROM table'
+     */
+    protected function _truncate(string $table): string
+    {
+        return 'DELETE FROM ' . $table;
+    }
+}

system/Database/SQLite3/Connection.php

@@ -0,0 +1,396 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use ErrorException;
+use Exception;
+use SQLite3;
+use stdClass;
+
+/**
+ * Connection for SQLite3
+ */
+class Connection extends BaseConnection
+{
+    /**
+     * Database driver
+     *
+     * @var string
+     */
+    public $DBDriver = 'SQLite3';
+
+    /**
+     * Identifier escape character
+     *
+     * @var string
+     */
+    public $escapeChar = '`';
+
+    /**
+     * Connect to the database.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function connect(bool $persistent = false)
+    {
+        if ($persistent && $this->DBDebug) {
+            throw new DatabaseException('SQLite3 doesn\'t support persistent connections.');
+        }
+
+        try {
+            if ($this->database !== ':memory:' && strpos($this->database, DIRECTORY_SEPARATOR) === false) {
+                $this->database = WRITEPATH . $this->database;
+            }
+
+            return (! $this->password)
+                ? new SQLite3($this->database)
+                : new SQLite3($this->database, SQLITE3_OPEN_READWRITE | SQLITE3_OPEN_CREATE, $this->password);
+        } catch (Exception $e) {
+            throw new DatabaseException('SQLite3 error: ' . $e->getMessage());
+        }
+    }
+
+    /**
+     * Keep or establish the connection if no queries have been sent for
+     * a length of time exceeding the server's idle timeout.
+     */
+    public function reconnect()
+    {
+        $this->close();
+        $this->initialize();
+    }
+
+    /**
+     * Close the database connection.
+     */
+    protected function _close()
+    {
+        $this->connID->close();
+    }
+
+    /**
+     * Select a specific database table to use.
+     */
+    public function setDatabase(string $databaseName): bool
+    {
+        return false;
+    }
+
+    /**
+     * Returns a string containing the version of the database being used.
+     */
+    public function getVersion(): string
+    {
+        if (isset($this->dataCache['version'])) {
+            return $this->dataCache['version'];
+        }
+
+        $version = SQLite3::version();
+
+        return $this->dataCache['version'] = $version['versionString'];
+    }
+
+    /**
+     * Execute the query
+     *
+     * @return mixed \SQLite3Result object or bool
+     */
+    protected function execute(string $sql)
+    {
+        try {
+            return $this->isWriteType($sql)
+                ? $this->connID->exec($sql)
+                : $this->connID->query($sql);
+        } catch (ErrorException $e) {
+            log_message('error', $e);
+            if ($this->DBDebug) {
+                throw $e;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Returns the total number of rows affected by this query.
+     */
+    public function affectedRows(): int
+    {
+        return $this->connID->changes();
+    }
+
+    /**
+     * Platform-dependant string escape
+     */
+    protected function _escapeString(string $str): string
+    {
+        return $this->connID->escapeString($str);
+    }
+
+    /**
+     * Generates the SQL for listing tables in a platform-dependent manner.
+     */
+    protected function _listTables(bool $prefixLimit = false): string
+    {
+        return 'SELECT "NAME" FROM "SQLITE_MASTER" WHERE "TYPE" = \'table\''
+               . ' AND "NAME" NOT LIKE \'sqlite!_%\' ESCAPE \'!\''
+               . (($prefixLimit !== false && $this->DBPrefix !== '')
+                    ? ' AND "NAME" LIKE \'' . $this->escapeLikeString($this->DBPrefix) . '%\' ' . sprintf($this->likeEscapeStr, $this->likeEscapeChar)
+                    : '');
+    }
+
+    /**
+     * Generates a platform-specific query string so that the column names can be fetched.
+     */
+    protected function _listColumns(string $table = ''): string
+    {
+        return 'PRAGMA TABLE_INFO(' . $this->protectIdentifiers($table, true, null, false) . ')';
+    }
+
+    /**
+     * @throws DatabaseException
+     *
+     * @return array|false
+     */
+    public function getFieldNames(string $table)
+    {
+        // Is there a cached result?
+        if (isset($this->dataCache['field_names'][$table])) {
+            return $this->dataCache['field_names'][$table];
+        }
+
+        if (empty($this->connID)) {
+            $this->initialize();
+        }
+
+        $sql = $this->_listColumns($table);
+
+        $query                                  = $this->query($sql);
+        $this->dataCache['field_names'][$table] = [];
+
+        foreach ($query->getResultArray() as $row) {
+            // Do we know from where to get the column's name?
+            if (! isset($key)) {
+                if (isset($row['column_name'])) {
+                    $key = 'column_name';
+                } elseif (isset($row['COLUMN_NAME'])) {
+                    $key = 'COLUMN_NAME';
+                } elseif (isset($row['name'])) {
+                    $key = 'name';
+                } else {
+                    // We have no other choice but to just get the first element's key.
+                    $key = key($row);
+                }
+            }
+
+            $this->dataCache['field_names'][$table][] = $row[$key];
+        }
+
+        return $this->dataCache['field_names'][$table];
+    }
+
+    /**
+     * Returns an array of objects with field data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _fieldData(string $table): array
+    {
+        if (false === $query = $this->query('PRAGMA TABLE_INFO(' . $this->protectIdentifiers($table, true, null, false) . ')')) {
+            throw new DatabaseException(lang('Database.failGetFieldData'));
+        }
+
+        $query = $query->getResultObject();
+
+        if (empty($query)) {
+            return [];
+        }
+
+        $retVal = [];
+
+        for ($i = 0, $c = count($query); $i < $c; $i++) {
+            $retVal[$i] = new stdClass();
+
+            $retVal[$i]->name        = $query[$i]->name;
+            $retVal[$i]->type        = $query[$i]->type;
+            $retVal[$i]->max_length  = null;
+            $retVal[$i]->default     = $query[$i]->dflt_value;
+            $retVal[$i]->primary_key = isset($query[$i]->pk) && (bool) $query[$i]->pk;
+            $retVal[$i]->nullable    = isset($query[$i]->notnull) && ! (bool) $query[$i]->notnull;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with index data
+     *
+     * @throws DatabaseException
+     *
+     * @return stdClass[]
+     */
+    protected function _indexData(string $table): array
+    {
+        // Get indexes
+        // Don't use PRAGMA index_list, so we can preserve index order
+        $sql = "SELECT name FROM sqlite_master WHERE type='index' AND tbl_name=" . $this->escape(strtolower($table));
+        if (($query = $this->query($sql)) === false) {
+            throw new DatabaseException(lang('Database.failGetIndexData'));
+        }
+        $query = $query->getResultObject();
+
+        $retVal = [];
+
+        foreach ($query as $row) {
+            $obj = new stdClass();
+
+            $obj->name = $row->name;
+
+            // Get fields for index
+            $obj->fields = [];
+
+            if (false === $fields = $this->query('PRAGMA index_info(' . $this->escape(strtolower($row->name)) . ')')) {
+                throw new DatabaseException(lang('Database.failGetIndexData'));
+            }
+
+            $fields = $fields->getResultObject();
+
+            foreach ($fields as $field) {
+                $obj->fields[] = $field->name;
+            }
+
+            $retVal[$obj->name] = $obj;
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns an array of objects with Foreign key data
+     *
+     * @return stdClass[]
+     */
+    protected function _foreignKeyData(string $table): array
+    {
+        if ($this->supportsForeignKeys() !== true) {
+            return [];
+        }
+
+        $tables = $this->listTables();
+
+        if (empty($tables)) {
+            return [];
+        }
+
+        $retVal = [];
+
+        foreach ($tables as $table) {
+            $query = $this->query("PRAGMA foreign_key_list({$table})")->getResult();
+
+            foreach ($query as $row) {
+                $obj                     = new stdClass();
+                $obj->constraint_name    = $row->from . ' to ' . $row->table . '.' . $row->to;
+                $obj->table_name         = $table;
+                $obj->foreign_table_name = $row->table;
+                $obj->sequence           = $row->seq;
+
+                $retVal[] = $obj;
+            }
+        }
+
+        return $retVal;
+    }
+
+    /**
+     * Returns platform-specific SQL to disable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _disableForeignKeyChecks()
+    {
+        return 'PRAGMA foreign_keys = OFF';
+    }
+
+    /**
+     * Returns platform-specific SQL to enable foreign key checks.
+     *
+     * @return string
+     */
+    protected function _enableForeignKeyChecks()
+    {
+        return 'PRAGMA foreign_keys = ON';
+    }
+
+    /**
+     * Returns the last error code and message.
+     * Must return this format: ['code' => string|int, 'message' => string]
+     * intval(code) === 0 means "no error".
+     *
+     * @return array<string, int|string>
+     */
+    public function error(): array
+    {
+        return [
+            'code'    => $this->connID->lastErrorCode(),
+            'message' => $this->connID->lastErrorMsg(),
+        ];
+    }
+
+    /**
+     * Insert ID
+     */
+    public function insertID(): int
+    {
+        return $this->connID->lastInsertRowID();
+    }
+
+    /**
+     * Begin Transaction
+     */
+    protected function _transBegin(): bool
+    {
+        return $this->connID->exec('BEGIN TRANSACTION');
+    }
+
+    /**
+     * Commit Transaction
+     */
+    protected function _transCommit(): bool
+    {
+        return $this->connID->exec('END TRANSACTION');
+    }
+
+    /**
+     * Rollback Transaction
+     */
+    protected function _transRollback(): bool
+    {
+        return $this->connID->exec('ROLLBACK');
+    }
+
+    /**
+     * Checks to see if the current install supports Foreign Keys
+     * and has them enabled.
+     */
+    public function supportsForeignKeys(): bool
+    {
+        $result = $this->simpleQuery('PRAGMA foreign_keys');
+
+        return (bool) $result;
+    }
+}

system/Database/SQLite3/Forge.php

@@ -0,0 +1,254 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use CodeIgniter\Database\BaseConnection;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Forge as BaseForge;
+
+/**
+ * Forge for SQLite3
+ */
+class Forge extends BaseForge
+{
+    /**
+     * DROP INDEX statement
+     *
+     * @var string
+     */
+    protected $dropIndexStr = 'DROP INDEX %s';
+
+    /**
+     * @var Connection
+     */
+    protected $db;
+
+    /**
+     * UNSIGNED support
+     *
+     * @var array|bool
+     */
+    protected $_unsigned = false;
+
+    /**
+     * NULL value representation in CREATE/ALTER TABLE statements
+     *
+     * @var string
+     *
+     * @internal
+     */
+    protected $null = 'NULL';
+
+    /**
+     * Constructor.
+     */
+    public function __construct(BaseConnection $db)
+    {
+        parent::__construct($db);
+
+        if (version_compare($this->db->getVersion(), '3.3', '<')) {
+            $this->createTableIfStr = false;
+            $this->dropTableIfStr   = false;
+        }
+    }
+
+    /**
+     * Create database
+     *
+     * @param bool $ifNotExists Whether to add IF NOT EXISTS condition
+     */
+    public function createDatabase(string $dbName, bool $ifNotExists = false): bool
+    {
+        // In SQLite, a database is created when you connect to the database.
+        // We'll return TRUE so that an error isn't generated.
+        return true;
+    }
+
+    /**
+     * Drop database
+     *
+     * @throws DatabaseException
+     */
+    public function dropDatabase(string $dbName): bool
+    {
+        // In SQLite, a database is dropped when we delete a file
+        if (! is_file($dbName)) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unable to drop the specified database.');
+            }
+
+            return false;
+        }
+
+        // We need to close the pseudo-connection first
+        $this->db->close();
+        if (! @unlink($dbName)) {
+            if ($this->db->DBDebug) {
+                throw new DatabaseException('Unable to drop the specified database.');
+            }
+
+            return false;
+        }
+
+        if (! empty($this->db->dataCache['db_names'])) {
+            $key = array_search(strtolower($dbName), array_map('strtolower', $this->db->dataCache['db_names']), true);
+            if ($key !== false) {
+                unset($this->db->dataCache['db_names'][$key]);
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * @param mixed $field
+     *
+     * @return array|string|null
+     */
+    protected function _alterTable(string $alterType, string $table, $field)
+    {
+        switch ($alterType) {
+            case 'DROP':
+                $sqlTable = new Table($this->db, $this);
+
+                $sqlTable->fromTable($table)
+                    ->dropColumn($field)
+                    ->run();
+
+                return '';
+
+            case 'CHANGE':
+                (new Table($this->db, $this))
+                    ->fromTable($table)
+                    ->modifyColumn($field)
+                    ->run();
+
+                return null;
+
+            default:
+                return parent::_alterTable($alterType, $table, $field);
+        }
+    }
+
+    /**
+     * Process column
+     */
+    protected function _processColumn(array $field): string
+    {
+        if ($field['type'] === 'TEXT' && strpos($field['length'], "('") === 0) {
+            $field['type'] .= ' CHECK(' . $this->db->escapeIdentifiers($field['name'])
+                . ' IN ' . $field['length'] . ')';
+        }
+
+        return $this->db->escapeIdentifiers($field['name'])
+            . ' ' . $field['type']
+            . $field['auto_increment']
+            . $field['null']
+            . $field['unique']
+            . $field['default'];
+    }
+
+    /**
+     * Process indexes
+     */
+    protected function _processIndexes(string $table): array
+    {
+        $sqls = [];
+
+        for ($i = 0, $c = count($this->keys); $i < $c; $i++) {
+            $this->keys[$i] = (array) $this->keys[$i];
+
+            for ($i2 = 0, $c2 = count($this->keys[$i]); $i2 < $c2; $i2++) {
+                if (! isset($this->fields[$this->keys[$i][$i2]])) {
+                    unset($this->keys[$i][$i2]);
+                }
+            }
+            if (count($this->keys[$i]) <= 0) {
+                continue;
+            }
+
+            if (in_array($i, $this->uniqueKeys, true)) {
+                $sqls[] = 'CREATE UNIQUE INDEX ' . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
+                    . ' ON ' . $this->db->escapeIdentifiers($table)
+                    . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';
+
+                continue;
+            }
+
+            $sqls[] = 'CREATE INDEX ' . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
+                . ' ON ' . $this->db->escapeIdentifiers($table)
+                . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';
+        }
+
+        return $sqls;
+    }
+
+    /**
+     * Field attribute TYPE
+     *
+     * Performs a data type mapping between different databases.
+     */
+    protected function _attributeType(array &$attributes)
+    {
+        switch (strtoupper($attributes['TYPE'])) {
+            case 'ENUM':
+            case 'SET':
+                $attributes['TYPE'] = 'TEXT';
+                break;
+
+            case 'BOOLEAN':
+                $attributes['TYPE'] = 'INT';
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Field attribute AUTO_INCREMENT
+     */
+    protected function _attributeAutoIncrement(array &$attributes, array &$field)
+    {
+        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true
+            && stripos($field['type'], 'int') !== false) {
+            $field['type']           = 'INTEGER PRIMARY KEY';
+            $field['default']        = '';
+            $field['null']           = '';
+            $field['unique']         = '';
+            $field['auto_increment'] = ' AUTOINCREMENT';
+
+            $this->primaryKeys = [];
+        }
+    }
+
+    /**
+     * Foreign Key Drop
+     *
+     * @throws DatabaseException
+     */
+    public function dropForeignKey(string $table, string $foreignName): bool
+    {
+        // If this version of SQLite doesn't support it, we're done here
+        if ($this->db->supportsForeignKeys() !== true) {
+            return true;
+        }
+
+        // Otherwise we have to copy the table and recreate
+        // without the foreign key being involved now
+        $sqlTable = new Table($this->db, $this);
+
+        return $sqlTable->fromTable($this->db->DBPrefix . $table)
+            ->dropForeignKey($foreignName)
+            ->run();
+    }
+}

system/Database/SQLite3/PreparedQuery.php

@@ -0,0 +1,91 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use BadMethodCallException;
+use CodeIgniter\Database\BasePreparedQuery;
+
+/**
+ * Prepared query for SQLite3
+ */
+class PreparedQuery extends BasePreparedQuery
+{
+    /**
+     * The SQLite3Result resource, or false.
+     *
+     * @var bool|Result
+     */
+    protected $result;
+
+    /**
+     * Prepares the query against the database, and saves the connection
+     * info necessary to execute the query later.
+     *
+     * NOTE: This version is based on SQL code. Child classes should
+     * override this method.
+     *
+     * @param array $options Passed to the connection's prepare statement.
+     *                       Unused in the MySQLi driver.
+     *
+     * @return $this
+     */
+    public function _prepare(string $sql, array $options = [])
+    {
+        if (! ($this->statement = $this->db->connID->prepare($sql))) {
+            $this->errorCode   = $this->db->connID->lastErrorCode();
+            $this->errorString = $this->db->connID->lastErrorMsg();
+        }
+
+        return $this;
+    }
+
+    /**
+     * Takes a new set of data and runs it against the currently
+     * prepared query. Upon success, will return a Results object.
+     *
+     * @todo finalize()
+     */
+    public function _execute(array $data): bool
+    {
+        if (! isset($this->statement)) {
+            throw new BadMethodCallException('You must call prepare before trying to execute a prepared statement.');
+        }
+
+        foreach ($data as $key => $item) {
+            // Determine the type string
+            if (is_int($item)) {
+                $bindType = SQLITE3_INTEGER;
+            } elseif (is_float($item)) {
+                $bindType = SQLITE3_FLOAT;
+            } else {
+                $bindType = SQLITE3_TEXT;
+            }
+
+            // Bind it
+            $this->statement->bindValue($key + 1, $item, $bindType);
+        }
+
+        $this->result = $this->statement->execute();
+
+        return $this->result !== false;
+    }
+
+    /**
+     * Returns the result object for the prepared query.
+     *
+     * @return mixed
+     */
+    public function _getResult()
+    {
+        return $this->result;
+    }
+}

system/Database/SQLite3/Result.php

@@ -0,0 +1,152 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use Closure;
+use CodeIgniter\Database\BaseResult;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Entity\Entity;
+use stdClass;
+
+/**
+ * Result for SQLite3
+ */
+class Result extends BaseResult
+{
+    /**
+     * Gets the number of fields in the result set.
+     */
+    public function getFieldCount(): int
+    {
+        return $this->resultID->numColumns();
+    }
+
+    /**
+     * Generates an array of column names in the result set.
+     */
+    public function getFieldNames(): array
+    {
+        $fieldNames = [];
+
+        for ($i = 0, $c = $this->getFieldCount(); $i < $c; $i++) {
+            $fieldNames[] = $this->resultID->columnName($i);
+        }
+
+        return $fieldNames;
+    }
+
+    /**
+     * Generates an array of objects representing field meta-data.
+     */
+    public function getFieldData(): array
+    {
+        static $dataTypes = [
+            SQLITE3_INTEGER => 'integer',
+            SQLITE3_FLOAT   => 'float',
+            SQLITE3_TEXT    => 'text',
+            SQLITE3_BLOB    => 'blob',
+            SQLITE3_NULL    => 'null',
+        ];
+
+        $retVal = [];
+        $this->resultID->fetchArray(SQLITE3_NUM);
+
+        for ($i = 0, $c = $this->getFieldCount(); $i < $c; $i++) {
+            $retVal[$i]             = new stdClass();
+            $retVal[$i]->name       = $this->resultID->columnName($i);
+            $type                   = $this->resultID->columnType($i);
+            $retVal[$i]->type       = $type;
+            $retVal[$i]->type_name  = $dataTypes[$type] ?? null;
+            $retVal[$i]->max_length = null;
+            $retVal[$i]->length     = null;
+        }
+        $this->resultID->reset();
+
+        return $retVal;
+    }
+
+    /**
+     * Frees the current result.
+     */
+    public function freeResult()
+    {
+        if (is_object($this->resultID)) {
+            $this->resultID->finalize();
+            $this->resultID = false;
+        }
+    }
+
+    /**
+     * Moves the internal pointer to the desired offset. This is called
+     * internally before fetching results to make sure the result set
+     * starts at zero.
+     *
+     * @throws DatabaseException
+     *
+     * @return mixed
+     */
+    public function dataSeek(int $n = 0)
+    {
+        if ($n !== 0) {
+            throw new DatabaseException('SQLite3 doesn\'t support seeking to other offset.');
+        }
+
+        return $this->resultID->reset();
+    }
+
+    /**
+     * Returns the result set as an array.
+     *
+     * Overridden by driver classes.
+     *
+     * @return mixed
+     */
+    protected function fetchAssoc()
+    {
+        return $this->resultID->fetchArray(SQLITE3_ASSOC);
+    }
+
+    /**
+     * Returns the result set as an object.
+     *
+     * Overridden by child classes.
+     *
+     * @return bool|object
+     */
+    protected function fetchObject(string $className = 'stdClass')
+    {
+        // No native support for fetching rows as objects
+        if (($row = $this->fetchAssoc()) === false) {
+            return false;
+        }
+
+        if ($className === 'stdClass') {
+            return (object) $row;
+        }
+
+        $classObj = new $className();
+
+        if (is_subclass_of($className, Entity::class)) {
+            return $classObj->setAttributes($row);
+        }
+
+        $classSet = Closure::bind(function ($key, $value) {
+            $this->{$key} = $value;
+        }, $classObj, $className);
+
+        foreach (array_keys($row) as $key) {
+            $classSet($key, $row[$key]);
+        }
+
+        return $classObj;
+    }
+}

system/Database/SQLite3/Table.php

@@ -0,0 +1,363 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use CodeIgniter\Database\Exceptions\DataException;
+
+/**
+ * Class Table
+ *
+ * Provides missing features for altering tables that are common
+ * in other supported databases, but are missing from SQLite.
+ * These are needed in order to support migrations during testing
+ * when another database is used as the primary engine, but
+ * SQLite in memory databases are used for faster test execution.
+ */
+class Table
+{
+    /**
+     * All of the fields this table represents.
+     *
+     * @var array
+     */
+    protected $fields = [];
+
+    /**
+     * All of the unique/primary keys in the table.
+     *
+     * @var array
+     */
+    protected $keys = [];
+
+    /**
+     * All of the foreign keys in the table.
+     *
+     * @var array
+     */
+    protected $foreignKeys = [];
+
+    /**
+     * The name of the table we're working with.
+     *
+     * @var string
+     */
+    protected $tableName;
+
+    /**
+     * The name of the table, with database prefix
+     *
+     * @var string
+     */
+    protected $prefixedTableName;
+
+    /**
+     * Database connection.
+     *
+     * @var Connection
+     */
+    protected $db;
+
+    /**
+     * Handle to our forge.
+     *
+     * @var Forge
+     */
+    protected $forge;
+
+    /**
+     * Table constructor.
+     */
+    public function __construct(Connection $db, Forge $forge)
+    {
+        $this->db    = $db;
+        $this->forge = $forge;
+    }
+
+    /**
+     * Reads an existing database table and
+     * collects all of the information needed to
+     * recreate this table.
+     *
+     * @return Table
+     */
+    public function fromTable(string $table)
+    {
+        $this->prefixedTableName = $table;
+
+        $prefix = $this->db->DBPrefix;
+
+        if (! empty($prefix) && strpos($table, $prefix) === 0) {
+            $table = substr($table, strlen($prefix));
+        }
+
+        if (! $this->db->tableExists($this->prefixedTableName)) {
+            throw DataException::forTableNotFound($this->prefixedTableName);
+        }
+
+        $this->tableName = $table;
+
+        $this->fields = $this->formatFields($this->db->getFieldData($table));
+
+        $this->keys = array_merge($this->keys, $this->formatKeys($this->db->getIndexData($table)));
+
+        $this->foreignKeys = $this->db->getForeignKeyData($table);
+
+        return $this;
+    }
+
+    /**
+     * Called after `fromTable` and any actions, like `dropColumn`, etc,
+     * to finalize the action. It creates a temp table, creates the new
+     * table with modifications, and copies the data over to the new table.
+     * Resets the connection dataCache to be sure changes are collected.
+     */
+    public function run(): bool
+    {
+        $this->db->query('PRAGMA foreign_keys = OFF');
+
+        $this->db->transStart();
+
+        $this->forge->renameTable($this->tableName, "temp_{$this->tableName}");
+
+        $this->forge->reset();
+
+        $this->createTable();
+
+        $this->copyData();
+
+        $this->forge->dropTable("temp_{$this->tableName}");
+
+        $success = $this->db->transComplete();
+
+        $this->db->query('PRAGMA foreign_keys = ON');
+
+        $this->db->resetDataCache();
+
+        return $success;
+    }
+
+    /**
+     * Drops columns from the table.
+     *
+     * @param array|string $columns
+     *
+     * @return Table
+     */
+    public function dropColumn($columns)
+    {
+        if (is_string($columns)) {
+            $columns = explode(',', $columns);
+        }
+
+        foreach ($columns as $column) {
+            $column = trim($column);
+            if (isset($this->fields[$column])) {
+                unset($this->fields[$column]);
+            }
+        }
+
+        return $this;
+    }
+
+    /**
+     * Modifies a field, including changing data type,
+     * renaming, etc.
+     *
+     * @return Table
+     */
+    public function modifyColumn(array $field)
+    {
+        $field = $field[0];
+
+        $oldName = $field['name'];
+        unset($field['name']);
+
+        $this->fields[$oldName] = $field;
+
+        return $this;
+    }
+
+    /**
+     * Drops a foreign key from this table so that
+     * it won't be recreated in the future.
+     *
+     * @return Table
+     */
+    public function dropForeignKey(string $column)
+    {
+        if (empty($this->foreignKeys)) {
+            return $this;
+        }
+
+        for ($i = 0; $i < count($this->foreignKeys); $i++) {
+            if ($this->foreignKeys[$i]->table_name !== $this->tableName) {
+                continue;
+            }
+
+            // The column name should be the first thing in the constraint name
+            if (strpos($this->foreignKeys[$i]->constraint_name, $column) !== 0) {
+                continue;
+            }
+
+            unset($this->foreignKeys[$i]);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Creates the new table based on our current fields.
+     *
+     * @return mixed
+     */
+    protected function createTable()
+    {
+        $this->dropIndexes();
+        $this->db->resetDataCache();
+
+        // Handle any modified columns.
+        $fields = [];
+
+        foreach ($this->fields as $name => $field) {
+            if (isset($field['new_name'])) {
+                $fields[$field['new_name']] = $field;
+
+                continue;
+            }
+
+            $fields[$name] = $field;
+        }
+
+        $this->forge->addField($fields);
+
+        // Unique/Index keys
+        if (is_array($this->keys)) {
+            foreach ($this->keys as $key) {
+                switch ($key['type']) {
+                    case 'primary':
+                        $this->forge->addPrimaryKey($key['fields']);
+                        break;
+
+                    case 'unique':
+                        $this->forge->addUniqueKey($key['fields']);
+                        break;
+
+                    case 'index':
+                        $this->forge->addKey($key['fields']);
+                        break;
+                }
+            }
+        }
+
+        return $this->forge->createTable($this->tableName);
+    }
+
+    /**
+     * Copies data from our old table to the new one,
+     * taking care map data correctly based on any columns
+     * that have been renamed.
+     */
+    protected function copyData()
+    {
+        $exFields  = [];
+        $newFields = [];
+
+        foreach ($this->fields as $name => $details) {
+            $newFields[] = $details['new_name'] ?? $name;
+            $exFields[]  = $name;
+        }
+
+        $exFields  = implode(', ', $exFields);
+        $newFields = implode(', ', $newFields);
+
+        $this->db->query("INSERT INTO {$this->prefixedTableName}({$newFields}) SELECT {$exFields} FROM {$this->db->DBPrefix}temp_{$this->tableName}");
+    }
+
+    /**
+     * Converts fields retrieved from the database to
+     * the format needed for creating fields with Forge.
+     *
+     * @param array|bool $fields
+     *
+     * @return mixed
+     */
+    protected function formatFields($fields)
+    {
+        if (! is_array($fields)) {
+            return $fields;
+        }
+
+        $return = [];
+
+        foreach ($fields as $field) {
+            $return[$field->name] = [
+                'type'    => $field->type,
+                'default' => $field->default,
+                'null'    => $field->nullable,
+            ];
+
+            if ($field->primary_key) {
+                $this->keys[$field->name] = [
+                    'fields' => [$field->name],
+                    'type'   => 'primary',
+                ];
+            }
+        }
+
+        return $return;
+    }
+
+    /**
+     * Converts keys retrieved from the database to
+     * the format needed to create later.
+     *
+     * @param mixed $keys
+     *
+     * @return mixed
+     */
+    protected function formatKeys($keys)
+    {
+        if (! is_array($keys)) {
+            return $keys;
+        }
+
+        $return = [];
+
+        foreach ($keys as $name => $key) {
+            $return[$name] = [
+                'fields' => $key->fields,
+                'type'   => 'index',
+            ];
+        }
+
+        return $return;
+    }
+
+    /**
+     * Attempts to drop all indexes and constraints
+     * from the database for this table.
+     */
+    protected function dropIndexes()
+    {
+        if (! is_array($this->keys) || $this->keys === []) {
+            return;
+        }
+
+        foreach ($this->keys as $name => $key) {
+            if ($key['type'] === 'primary' || $key['type'] === 'unique') {
+                continue;
+            }
+
+            $this->db->query("DROP INDEX IF EXISTS '{$name}'");
+        }
+    }
+}

system/Database/SQLite3/Utils.php

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\SQLite3;
+
+use CodeIgniter\Database\BaseUtils;
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+/**
+ * Utils for SQLite3
+ */
+class Utils extends BaseUtils
+{
+    /**
+     * OPTIMIZE TABLE statement
+     *
+     * @var string
+     */
+    protected $optimizeTable = 'REINDEX %s';
+
+    /**
+     * Platform dependent version of the backup function.
+     *
+     * @return mixed
+     */
+    public function _backup(?array $prefs = null)
+    {
+        throw new DatabaseException('Unsupported feature of the database platform you are using.');
+    }
+}

system/Database/Seeder.php

@@ -0,0 +1,193 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\CLI\CLI;
+use Config\Database;
+use Faker\Factory;
+use Faker\Generator;
+use InvalidArgumentException;
+
+/**
+ * Class Seeder
+ */
+class Seeder
+{
+    /**
+     * The name of the database group to use.
+     *
+     * @var string
+     */
+    protected $DBGroup;
+
+    /**
+     * Where we can find the Seed files.
+     *
+     * @var string
+     */
+    protected $seedPath;
+
+    /**
+     * An instance of the main Database configuration
+     *
+     * @var Database
+     */
+    protected $config;
+
+    /**
+     * Database Connection instance
+     *
+     * @var BaseConnection
+     */
+    protected $db;
+
+    /**
+     * Database Forge instance.
+     *
+     * @var Forge
+     */
+    protected $forge;
+
+    /**
+     * If true, will not display CLI messages.
+     *
+     * @var bool
+     */
+    protected $silent = false;
+
+    /**
+     * Faker Generator instance.
+     *
+     * @var Generator|null
+     *
+     * @deprecated
+     */
+    private static $faker;
+
+    /**
+     * Seeder constructor.
+     */
+    public function __construct(Database $config, ?BaseConnection $db = null)
+    {
+        $this->seedPath = $config->filesPath ?? APPPATH . 'Database/';
+
+        if (empty($this->seedPath)) {
+            throw new InvalidArgumentException('Invalid filesPath set in the Config\Database.');
+        }
+
+        $this->seedPath = rtrim($this->seedPath, '\\/') . '/Seeds/';
+
+        if (! is_dir($this->seedPath)) {
+            throw new InvalidArgumentException('Unable to locate the seeds directory. Please check Config\Database::filesPath');
+        }
+
+        $this->config = &$config;
+
+        $db = $db ?? Database::connect($this->DBGroup);
+
+        $this->db    = &$db;
+        $this->forge = Database::forge($this->DBGroup);
+    }
+
+    /**
+     * Gets the Faker Generator instance.
+     *
+     * @deprecated
+     */
+    public static function faker(): ?Generator
+    {
+        if (self::$faker === null && class_exists(Factory::class)) {
+            self::$faker = Factory::create();
+        }
+
+        return self::$faker;
+    }
+
+    /**
+     * Loads the specified seeder and runs it.
+     *
+     * @throws InvalidArgumentException
+     */
+    public function call(string $class)
+    {
+        $class = trim($class);
+
+        if ($class === '') {
+            throw new InvalidArgumentException('No seeder was specified.');
+        }
+
+        if (strpos($class, '\\') === false) {
+            $path = $this->seedPath . str_replace('.php', '', $class) . '.php';
+
+            if (! is_file($path)) {
+                throw new InvalidArgumentException('The specified seeder is not a valid file: ' . $path);
+            }
+
+            // Assume the class has the correct namespace
+            // @codeCoverageIgnoreStart
+            $class = APP_NAMESPACE . '\Database\Seeds\\' . $class;
+
+            if (! class_exists($class, false)) {
+                require_once $path;
+            }
+            // @codeCoverageIgnoreEnd
+        }
+
+        /** @var Seeder $seeder */
+        $seeder = new $class($this->config);
+        $seeder->setSilent($this->silent)->run();
+
+        unset($seeder);
+
+        if (is_cli() && ! $this->silent) {
+            CLI::write("Seeded: {$class}", 'green');
+        }
+    }
+
+    /**
+     * Sets the location of the directory that seed files can be located in.
+     *
+     * @return $this
+     */
+    public function setPath(string $path)
+    {
+        $this->seedPath = rtrim($path, '\\/') . '/';
+
+        return $this;
+    }
+
+    /**
+     * Sets the silent treatment.
+     *
+     * @return $this
+     */
+    public function setSilent(bool $silent)
+    {
+        $this->silent = $silent;
+
+        return $this;
+    }
+
+    /**
+     * Run the database seeds. This is where the magic happens.
+     *
+     * Child classes must implement this method and take care
+     * of inserting their data here.
+     *
+     * @return mixed
+     *
+     * @codeCoverageIgnore
+     */
+    public function run()
+    {
+    }
+}