system/database/drivers/mysql/mysql_driver.php

<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * NOTICE OF LICENSE
 *
 * Licensed under the Open Software License version 3.0
 *
 * This source file is subject to the Open Software License (OSL 3.0) that is
 * bundled with this package in the files license.txt / license.rst.  It is
 * also available through the world wide web at this URL:
 * http://opensource.org/licenses/OSL-3.0
 * If you did not receive a copy of the license and are unable to obtain it
 * through the world wide web, please send an email to
 * licensing@ellislab.com so we can send you a copy immediately.
 *
 * @package		CodeIgniter
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
 * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * MySQL Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package		CodeIgniter
 * @subpackage	Drivers
 * @category	Database
 * @author		EllisLab Dev Team
 * @link		http://codeigniter.com/user_guide/database/
 */
class CI_DB_mysql_driver extends CI_DB {

	/**
	 * Database driver
	 *
	 * @var	string
	 */
	public $dbdriver = 'mysql';

	/**
	 * Compression flag
	 *
	 * @var	bool
	 */
	public $compress = FALSE;

	/**
	 * 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 $delete_hack = TRUE;

	// --------------------------------------------------------------------

	/**
	 * Identifier escape character
	 *
	 * @var	string
	 */
	protected $_escape_char = '`';

	// --------------------------------------------------------------------

	/**
	 * Class constructor
	 *
	 * @param	array	$params
	 * @return	void
	 */
	public function __construct($params)
	{
		parent::__construct($params);

		if ( ! empty($this->port))
		{
			$this->hostname .= ':'.$this->port;
		}
	}

	// --------------------------------------------------------------------

	/**
	 * Non-persistent database connection
	 *
	 * @param	bool	$persistent
	 * @return	resource
	 */
	public function db_connect($persistent = FALSE)
	{
		$client_flags = ($this->compress === FALSE) ? 0 : MYSQL_CLIENT_COMPRESS;

		if ($this->encrypt === TRUE)
		{
			$client_flags = $client_flags | MYSQL_CLIENT_SSL;
		}

		return ($persistent === TRUE)
			? @mysql_pconnect($this->hostname, $this->username, $this->password, $client_flags)
			: @mysql_connect($this->hostname, $this->username, $this->password, TRUE, $client_flags);
	}

	// --------------------------------------------------------------------

	/**
	 * Persistent database connection
	 *
	 * @return	resource
	 */
	public function db_pconnect()
	{
		return $this->db_connect(TRUE);
	}

	// --------------------------------------------------------------------

	/**
	 * Reconnect
	 *
	 * Keep / reestablish the db connection if no queries have been
	 * sent for a length of time exceeding the server's idle timeout
	 *
	 * @return	void
	 */
	public function reconnect()
	{
		if (mysql_ping($this->conn_id) === FALSE)
		{
			$this->conn_id = FALSE;
		}
	}

	// --------------------------------------------------------------------

	/**
	 * Select the database
	 *
	 * @param	string	$database
	 * @return	bool
	 */
	public function db_select($database = '')
	{
		if ($database === '')
		{
			$database = $this->database;
		}

		if (@mysql_select_db($database, $this->conn_id))
		{
			$this->database = $database;
			return TRUE;
		}

		return FALSE;
	}

	// --------------------------------------------------------------------

	/**
	 * Set client character set
	 *
	 * @param	string	$charset
	 * @return	bool
	 */
	protected function _db_set_charset($charset)
	{
		return @mysql_set_charset($charset, $this->conn_id);
	}

	// --------------------------------------------------------------------

	/**
	 * Database version number
	 *
	 * @return	string
	 */
	public function version()
	{
		return isset($this->data_cache['version'])
			? $this->data_cache['version']
			: $this->data_cache['version'] = @mysql_get_server_info($this->conn_id);
	}

	// --------------------------------------------------------------------

	/**
	 * Execute the query
	 *
	 * @param	string	$sql	an SQL query
	 * @return	mixed
	 */
	protected function _execute($sql)
	{
		return @mysql_query($this->_prep_query($sql), $this->conn_id);
	}

	// --------------------------------------------------------------------

	/**
	 * Prep the query
	 *
	 * If needed, each database adapter can prep the query string
	 *
	 * @param	string	$sql	an SQL query
	 * @return	string
	 */
	protected function _prep_query($sql)
	{
		// mysql_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 ($this->delete_hack === TRUE && preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $sql))
		{
			return preg_replace('/^\s*DELETE\s+FROM\s+(\S+)\s*$/', 'DELETE FROM \\1 WHERE 1=1', $sql);
		}

		return $sql;
	}

	// --------------------------------------------------------------------

	/**
	 * Begin Transaction
	 *
	 * @param	bool	$test_mode
	 * @return	bool
	 */
	public function trans_begin($test_mode = FALSE)
	{
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
		{
			return TRUE;
		}

		// Reset the transaction failure flag.
		// If the $test_mode flag is set to TRUE transactions will be rolled back
		// even if the queries produce a successful result.
		$this->_trans_failure = ($test_mode === TRUE);

		$this->simple_query('SET AUTOCOMMIT=0');
		$this->simple_query('START TRANSACTION'); // can also be BEGIN or BEGIN WORK
		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Commit Transaction
	 *
	 * @return	bool
	 */
	public function trans_commit()
	{
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
		{
			return TRUE;
		}

		$this->simple_query('COMMIT');
		$this->simple_query('SET AUTOCOMMIT=1');
		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Rollback Transaction
	 *
	 * @return	bool
	 */
	public function trans_rollback()
	{
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
		{
			return TRUE;
		}

		$this->simple_query('ROLLBACK');
		$this->simple_query('SET AUTOCOMMIT=1');
		return TRUE;
	}

	// --------------------------------------------------------------------

	/**
	 * Escape String
	 *
	 * @param	string	$str
	 * @param	bool	$like	Whether or not the string will be used in a LIKE condition
	 * @return	string
	 */
	public function escape_str($str, $like = FALSE)
	{
		if (is_array($str))
		{
			foreach ($str as $key => $val)
	   		{
				$str[$key] = $this->escape_str($val, $like);
	   		}

	   		return $str;
	   	}

		$str = is_resource($this->conn_id) ? mysql_real_escape_string($str, $this->conn_id) : addslashes($str);

		// escape LIKE condition wildcards
		if ($like === TRUE)
		{
			return str_replace(array($this->_like_escape_chr, '%', '_'),
						array($this->_like_escape_chr.$this->_like_escape_chr, $this->_like_escape_chr.'%', $this->_like_escape_chr.'_'),
						$str);
		}

		return $str;
	}

	// --------------------------------------------------------------------

	/**
	 * Affected Rows
	 *
	 * @return	int
	 */
	public function affected_rows()
	{
		return @mysql_affected_rows($this->conn_id);
	}

	// --------------------------------------------------------------------

	/**
	 * Insert ID
	 *
	 * @return	int
	 */
	public function insert_id()
	{
		return @mysql_insert_id($this->conn_id);
	}

	// --------------------------------------------------------------------

	/**
	 * List table query
	 *
	 * Generates a platform-specific query string so that the table names can be fetched
	 *
	 * @param	bool	$prefix_limit
	 * @return	string
	 */
	protected function _list_tables($prefix_limit = FALSE)
	{
		$sql = 'SHOW TABLES FROM '.$this->escape_identifiers($this->database);

		if ($prefix_limit !== FALSE && $this->dbprefix !== '')
		{
			return $sql." LIKE '".$this->escape_like_str($this->dbprefix)."%'";
		}

		return $sql;
	}

	// --------------------------------------------------------------------

	/**
	 * Show column query
	 *
	 * Generates a platform-specific query string so that the column names can be fetched
	 *
	 * @param	string	$table
	 * @return	string
	 */
	protected function _list_columns($table = '')
	{
		return 'SHOW COLUMNS FROM '.$this->protect_identifiers($table, TRUE, NULL, FALSE);
	}

	// --------------------------------------------------------------------

	/**
	 * Returns an object with field data
	 *
	 * @param	string	$table
	 * @return	object
	 */
	public function field_data($table = '')
	{
		if ($table === '')
		{
			return ($this->db_debug) ? $this->display_error('db_field_param_missing') : FALSE;
		}

		$query = $this->query('DESCRIBE '.$this->protect_identifiers($table, TRUE, NULL, FALSE));
		$query = $query->result_object();

		$retval = array();
		for ($i = 0, $c = count($query); $i < $c; $i++)
		{
			preg_match('/([a-z]+)(\(\d+\))?/', $query[$i]->Type, $matches);

			$retval[$i]			= new stdClass();
			$retval[$i]->name		= $query[$i]->Field;
			$retval[$i]->type		= empty($matches[1]) ? NULL : $matches[1];
			$retval[$i]->default		= $query[$i]->Default;
			$retval[$i]->max_length		= empty($matches[2]) ? NULL : preg_replace('/[^\d]/', '', $matches[2]);
			$retval[$i]->primary_key	= (int) ($query[$i]->Key === 'PRI');
		}

		return $retval;
	}

	// --------------------------------------------------------------------

	/**
	 * Error
	 *
	 * Returns an array containing code and message of the last
	 * database error that has occured.
	 *
	 * @return	array
	 */
	public function error()
	{
		return array('code' => mysql_errno($this->conn_id), 'message' => mysql_error($this->conn_id));
	}

	// --------------------------------------------------------------------

	/**
	 * Update_Batch statement
	 *
	 * Generates a platform-specific batch update string from the supplied data
	 *
	 * @param	string	$table	Table name
	 * @param	array	$values	Update data
	 * @param	string	$index	WHERE key
	 * @return	string
	 */
	protected function _update_batch($table, $values, $index)
	{
		$ids = array();
		foreach ($values as $key => $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 '.$table.' SET '.substr($cases, 0, -2).$this->_compile_wh('qb_where');
	}

	// --------------------------------------------------------------------

	/**
	 * FROM tables
	 *
	 * Groups tables in FROM clauses if needed, so there is no confusion
	 * about operator precedence.
	 *
	 * @return	string
	 */
	protected function _from_tables()
	{
		if ( ! empty($this->qb_join) && count($this->qb_from) > 1)
		{
			return '('.implode(', ', $this->qb_from).')';
		}

		return implode(', ', $this->qb_from);
	}

	// --------------------------------------------------------------------

	/**
	 * Close DB Connection
	 *
	 * @return	void
	 */
	protected function _close()
	{
		@mysql_close($this->conn_id);
	}

}

/* End of file mysql_driver.php */
/* Location: ./system/database/drivers/mysql/mysql_driver.php */