/includes/external/MDB2/Driver/mysqli.php

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<?php
// vim: set et ts=4 sw=4 fdm=marker:
// +----------------------------------------------------------------------+
// | PHP versions 4 and 5                                                 |
// +----------------------------------------------------------------------+
// | Copyright (c) 1998-2006 Manuel Lemos, Tomas V.V.Cox,                 |
// | Stig. S. Bakken, Lukas Smith                                         |
// | All rights reserved.                                                 |
// +----------------------------------------------------------------------+
// | MDB2 is a merge of PEAR DB and Metabases that provides a unified DB  |
// | API as well as database abstraction for PHP applications.            |
// | This LICENSE is in the BSD license style.                            |
// |                                                                      |
// | Redistribution and use in source and binary forms, with or without   |
// | modification, are permitted provided that the following conditions   |
// | are met:                                                             |
// |                                                                      |
// | Redistributions of source code must retain the above copyright       |
// | notice, this list of conditions and the following disclaimer.        |
// |                                                                      |
// | Redistributions in binary form must reproduce the above copyright    |
// | notice, this list of conditions and the following disclaimer in the  |
// | documentation and/or other materials provided with the distribution. |
// |                                                                      |
// | Neither the name of Manuel Lemos, Tomas V.V.Cox, Stig. S. Bakken,    |
// | Lukas Smith nor the names of his contributors may be used to endorse |
// | or promote products derived from this software without specific prior|
// | written permission.                                                  |
// |                                                                      |
// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS  |
// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT    |
// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS    |
// | FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE      |
// | REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,          |
// | INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
// | BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS|
// |  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED  |
// | AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT          |
// | LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY|
// | WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE          |
// | POSSIBILITY OF SUCH DAMAGE.                                          |
// +----------------------------------------------------------------------+
// | Author: Lukas Smith <smith@pooteeweet.org>                           |
// +----------------------------------------------------------------------+
//
// $Id: mysqli.php,v 1.188 2008/03/13 03:31:55 afz Exp $
//

/**
 * MDB2 MySQLi driver
 *
 * @package MDB2
 * @category Database
 * @author  Lukas Smith <smith@pooteeweet.org>
 */
class MDB2_Driver_mysqli extends MDB2_Driver_Common
{
    // {{{ properties

    var $string_quoting = array('start' => "'", 'end' => "'", 'escape' => '\\', 'escape_pattern' => '\\');

    var $identifier_quoting = array('start' => '`', 'end' => '`', 'escape' => '`');

    var $sql_comments = array(
        array('start' => '-- ', 'end' => "\n", 'escape' => false),
        array('start' => '#', 'end' => "\n", 'escape' => false),
        array('start' => '/*', 'end' => '*/', 'escape' => false),
    );

    var $server_capabilities_checked = false;

    var $start_transaction = false;

    var $varchar_max_length = 255;

    // }}}
    // {{{ constructor

    /**
     * Constructor
     */
    function __construct()
    {
        parent::__construct();

        $this->phptype = 'mysqli';
        $this->dbsyntax = 'mysql';

        $this->supported['sequences'] = 'emulated';
        $this->supported['indexes'] = true;
        $this->supported['affected_rows'] = true;
        $this->supported['transactions'] = false;
        $this->supported['savepoints'] = false;
        $this->supported['summary_functions'] = true;
        $this->supported['order_by_text'] = true;
        $this->supported['current_id'] = 'emulated';
        $this->supported['limit_queries'] = true;
        $this->supported['LOBs'] = true;
        $this->supported['replace'] = true;
        $this->supported['sub_selects'] = 'emulated';
        $this->supported['triggers'] = false;
        $this->supported['auto_increment'] = true;
        $this->supported['primary_key'] = true;
        $this->supported['result_introspection'] = true;
        $this->supported['prepared_statements'] = 'emulated';
        $this->supported['identifier_quoting'] = true;
        $this->supported['pattern_escaping'] = true;
        $this->supported['new_link'] = true;

        $this->options['DBA_username'] = false;
        $this->options['DBA_password'] = false;
        $this->options['default_table_type'] = '';
        $this->options['multi_query'] = false;
        $this->options['max_identifiers_length'] = 64;

        $this->_reCheckSupportedOptions();
    }

    // }}}
    // {{{ _reCheckSupportedOptions()

    /**
     * If the user changes certain options, other capabilities may depend
     * on the new settings, so we need to check them (again).
     *
     * @access private
     */
    function _reCheckSupportedOptions()
    {
        $this->supported['transactions'] = $this->options['use_transactions'];
        $this->supported['savepoints']   = $this->options['use_transactions'];
        if ($this->options['default_table_type']) {
            switch (strtoupper($this->options['default_table_type'])) {
            case 'BLACKHOLE':
            case 'MEMORY':
            case 'ARCHIVE':
            case 'CSV':
            case 'HEAP':
            case 'ISAM':
            case 'MERGE':
            case 'MRG_ISAM':
            case 'ISAM':
            case 'MRG_MYISAM':
            case 'MYISAM':
                $this->supported['savepoints']   = false;
                $this->supported['transactions'] = false;
                $this->warnings[] = $this->options['default_table_type'] .
                    ' is not a supported default table type';
                break;
            }
        }
    }

    // }}}
    // {{{ function setOption($option, $value)

    /**
     * set the option for the db class
     *
     * @param   string  option name
     * @param   mixed   value for the option
     *
     * @return  mixed   MDB2_OK or MDB2 Error Object
     *
     * @access  public
     */
    function setOption($option, $value)
    {
        $res = parent::setOption($option, $value);
        $this->_reCheckSupportedOptions();
    }

    // }}}
    // {{{ errorInfo()

    /**
     * This method is used to collect information about an error
     *
     * @param integer $error
     * @return array
     * @access public
     */
    function errorInfo($error = null)
    {
        if ($this->connection) {
            $native_code = @mysqli_errno($this->connection);
            $native_msg  = @mysqli_error($this->connection);
        } else {
            $native_code = @mysqli_connect_errno();
            $native_msg  = @mysqli_connect_error();
        }
        if (is_null($error)) {
            static $ecode_map;
            if (empty($ecode_map)) {
                $ecode_map = array(
                    1000 => MDB2_ERROR_INVALID, //hashchk
                    1001 => MDB2_ERROR_INVALID, //isamchk
                    1004 => MDB2_ERROR_CANNOT_CREATE,
                    1005 => MDB2_ERROR_CANNOT_CREATE,
                    1006 => MDB2_ERROR_CANNOT_CREATE,
                    1007 => MDB2_ERROR_ALREADY_EXISTS,
                    1008 => MDB2_ERROR_CANNOT_DROP,
                    1009 => MDB2_ERROR_CANNOT_DROP,
                    1010 => MDB2_ERROR_CANNOT_DROP,
                    1011 => MDB2_ERROR_CANNOT_DELETE,
                    1022 => MDB2_ERROR_ALREADY_EXISTS,
                    1029 => MDB2_ERROR_NOT_FOUND,
                    1032 => MDB2_ERROR_NOT_FOUND,
                    1044 => MDB2_ERROR_ACCESS_VIOLATION,
                    1045 => MDB2_ERROR_ACCESS_VIOLATION,
                    1046 => MDB2_ERROR_NODBSELECTED,
                    1048 => MDB2_ERROR_CONSTRAINT,
                    1049 => MDB2_ERROR_NOSUCHDB,
                    1050 => MDB2_ERROR_ALREADY_EXISTS,
                    1051 => MDB2_ERROR_NOSUCHTABLE,
                    1054 => MDB2_ERROR_NOSUCHFIELD,
                    1060 => MDB2_ERROR_ALREADY_EXISTS,
                    1061 => MDB2_ERROR_ALREADY_EXISTS,
                    1062 => MDB2_ERROR_ALREADY_EXISTS,
                    1064 => MDB2_ERROR_SYNTAX,
                    1067 => MDB2_ERROR_INVALID,
                    1072 => MDB2_ERROR_NOT_FOUND,
                    1086 => MDB2_ERROR_ALREADY_EXISTS,
                    1091 => MDB2_ERROR_NOT_FOUND,
                    1100 => MDB2_ERROR_NOT_LOCKED,
                    1109 => MDB2_ERROR_NOT_FOUND,
                    1125 => MDB2_ERROR_ALREADY_EXISTS,
                    1136 => MDB2_ERROR_VALUE_COUNT_ON_ROW,
                    1138 => MDB2_ERROR_INVALID,
                    1142 => MDB2_ERROR_ACCESS_VIOLATION,
                    1143 => MDB2_ERROR_ACCESS_VIOLATION,
                    1146 => MDB2_ERROR_NOSUCHTABLE,
                    1149 => MDB2_ERROR_SYNTAX,
                    1169 => MDB2_ERROR_CONSTRAINT,
                    1176 => MDB2_ERROR_NOT_FOUND,
                    1177 => MDB2_ERROR_NOSUCHTABLE,
                    1213 => MDB2_ERROR_DEADLOCK,
                    1216 => MDB2_ERROR_CONSTRAINT,
                    1217 => MDB2_ERROR_CONSTRAINT,
                    1227 => MDB2_ERROR_ACCESS_VIOLATION,
                    1235 => MDB2_ERROR_CANNOT_CREATE,
                    1299 => MDB2_ERROR_INVALID_DATE,
                    1300 => MDB2_ERROR_INVALID,
                    1304 => MDB2_ERROR_ALREADY_EXISTS,
                    1305 => MDB2_ERROR_NOT_FOUND,
                    1306 => MDB2_ERROR_CANNOT_DROP,
                    1307 => MDB2_ERROR_CANNOT_CREATE,
                    1334 => MDB2_ERROR_CANNOT_ALTER,
                    1339 => MDB2_ERROR_NOT_FOUND,
                    1356 => MDB2_ERROR_INVALID,
                    1359 => MDB2_ERROR_ALREADY_EXISTS,
                    1360 => MDB2_ERROR_NOT_FOUND,
                    1363 => MDB2_ERROR_NOT_FOUND,
                    1365 => MDB2_ERROR_DIVZERO,
                    1451 => MDB2_ERROR_CONSTRAINT,
                    1452 => MDB2_ERROR_CONSTRAINT,
                    1542 => MDB2_ERROR_CANNOT_DROP,
                    1546 => MDB2_ERROR_CONSTRAINT,
                    1582 => MDB2_ERROR_CONSTRAINT,
                    2003 => MDB2_ERROR_CONNECT_FAILED,
                    2019 => MDB2_ERROR_INVALID,
                );
            }
            if ($this->options['portability'] & MDB2_PORTABILITY_ERRORS) {
                $ecode_map[1022] = MDB2_ERROR_CONSTRAINT;
                $ecode_map[1048] = MDB2_ERROR_CONSTRAINT_NOT_NULL;
                $ecode_map[1062] = MDB2_ERROR_CONSTRAINT;
            } else {
                // Doing this in case mode changes during runtime.
                $ecode_map[1022] = MDB2_ERROR_ALREADY_EXISTS;
                $ecode_map[1048] = MDB2_ERROR_CONSTRAINT;
                $ecode_map[1062] = MDB2_ERROR_ALREADY_EXISTS;
            }
            if (isset($ecode_map[$native_code])) {
                $error = $ecode_map[$native_code];
            }
        }
        return array($error, $native_code, $native_msg);
    }

    // }}}
    // {{{ escape()

    /**
     * Quotes a string so it can be safely used in a query. It will quote
     * the text so it can safely be used within a query.
     *
     * @param   string  the input string to quote
     * @param   bool    escape wildcards
     *
     * @return  string  quoted string
     *
     * @access  public
     */
    function escape($text, $escape_wildcards = false)
    {
        if ($escape_wildcards) {
            $text = $this->escapePattern($text);
        }
        $connection = $this->getConnection();
        if (PEAR::isError($connection)) {
            return $connection;
        }
        $text = @mysqli_real_escape_string($connection, $text);
        return $text;
    }

    // }}}
    // {{{ beginTransaction()

    /**
     * Start a transaction or set a savepoint.
     *
     * @param   string  name of a savepoint to set
     * @return  mixed   MDB2_OK on success, a MDB2 error on failure
     *
     * @access  public
     */
    function beginTransaction($savepoint = null)
    {
        $this->debug('Starting transaction/savepoint', __FUNCTION__, array('is_manip' => true, 'savepoint' => $savepoint));
        $this->_getServerCapabilities();
        if (!is_null($savepoint)) {
            if (!$this->supports('savepoints')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'savepoints are not supported', __FUNCTION__);
            }
            if (!$this->in_transaction) {
                return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                    'savepoint cannot be released when changes are auto committed', __FUNCTION__);
            }
            $query = 'SAVEPOINT '.$savepoint;
            return $this->_doQuery($query, true);
        } elseif ($this->in_transaction) {
            return MDB2_OK;  //nothing to do
        }
        $query = $this->start_transaction ? 'START TRANSACTION' : 'SET AUTOCOMMIT = 1';
        $result =& $this->_doQuery($query, true);
        if (PEAR::isError($result)) {
            return $result;
        }
        $this->in_transaction = true;
        return MDB2_OK;
    }

    // }}}
    // {{{ commit()

    /**
     * Commit the database changes done during a transaction that is in
     * progress or release a savepoint. This function may only be called when
     * auto-committing is disabled, otherwise it will fail. Therefore, a new
     * transaction is implicitly started after committing the pending changes.
     *
     * @param   string  name of a savepoint to release
     * @return  mixed   MDB2_OK on success, a MDB2 error on failure
     *
     * @access  public
     */
    function commit($savepoint = null)
    {
        $this->debug('Committing transaction/savepoint', __FUNCTION__, array('is_manip' => true, 'savepoint' => $savepoint));
        if (!$this->in_transaction) {
            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                'commit/release savepoint cannot be done changes are auto committed', __FUNCTION__);
        }
        if (!is_null($savepoint)) {
            if (!$this->supports('savepoints')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'savepoints are not supported', __FUNCTION__);
            }
            $server_info = $this->getServerVersion();
            if (version_compare($server_info['major'].'.'.$server_info['minor'].'.'.$server_info['patch'], '5.0.3', '<')) {
                return MDB2_OK;
            }
            $query = 'RELEASE SAVEPOINT '.$savepoint;
            return $this->_doQuery($query, true);
        }

        if (!$this->supports('transactions')) {
            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'transactions are not supported', __FUNCTION__);
        }

        $result =& $this->_doQuery('COMMIT', true);
        if (PEAR::isError($result)) {
            return $result;
        }
        if (!$this->start_transaction) {
            $query = 'SET AUTOCOMMIT = 0';
            $result =& $this->_doQuery($query, true);
            if (PEAR::isError($result)) {
                return $result;
            }
        }
        $this->in_transaction = false;
        return MDB2_OK;
    }

    // }}}
    // {{{ rollback()

    /**
     * Cancel any database changes done during a transaction or since a specific
     * savepoint that is in progress. This function may only be called when
     * auto-committing is disabled, otherwise it will fail. Therefore, a new
     * transaction is implicitly started after canceling the pending changes.
     *
     * @param   string  name of a savepoint to rollback to
     * @return  mixed   MDB2_OK on success, a MDB2 error on failure
     *
     * @access  public
     */
    function rollback($savepoint = null)
    {
        $this->debug('Rolling back transaction/savepoint', __FUNCTION__, array('is_manip' => true, 'savepoint' => $savepoint));
        if (!$this->in_transaction) {
            return $this->raiseError(MDB2_ERROR_INVALID, null, null,
                'rollback cannot be done changes are auto committed', __FUNCTION__);
        }
        if (!is_null($savepoint)) {
            if (!$this->supports('savepoints')) {
                return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                    'savepoints are not supported', __FUNCTION__);
            }
            $query = 'ROLLBACK TO SAVEPOINT '.$savepoint;
            return $this->_doQuery($query, true);
        }

        $query = 'ROLLBACK';
        $result =& $this->_doQuery($query, true);
        if (PEAR::isError($result)) {
            return $result;
        }
        if (!$this->start_transaction) {
            $query = 'SET AUTOCOMMIT = 0';
            $result =& $this->_doQuery($query, true);
            if (PEAR::isError($result)) {
                return $result;
            }
        }
        $this->in_transaction = false;
        return MDB2_OK;
    }

    // }}}
    // {{{ function setTransactionIsolation()

    /**
     * Set the transacton isolation level.
     *
     * @param   string  standard isolation level
     *                  READ UNCOMMITTED (allows dirty reads)
     *                  READ COMMITTED (prevents dirty reads)
     *                  REPEATABLE READ (prevents nonrepeatable reads)
     *                  SERIALIZABLE (prevents phantom reads)
     * @return  mixed   MDB2_OK on success, a MDB2 error on failure
     *
     * @access  public
     * @since   2.1.1
     */
    function setTransactionIsolation($isolation)
    {
        $this->debug('Setting transaction isolation level', __FUNCTION__, array('is_manip' => true));
        if (!$this->supports('transactions')) {
            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'transactions are not supported', __FUNCTION__);
        }
        switch ($isolation) {
        case 'READ UNCOMMITTED':
        case 'READ COMMITTED':
        case 'REPEATABLE READ':
        case 'SERIALIZABLE':
            break;
        default:
            return $this->raiseError(MDB2_ERROR_UNSUPPORTED, null, null,
                'isolation level is not supported: '.$isolation, __FUNCTION__);
        }

        $query = "SET SESSION TRANSACTION ISOLATION LEVEL $isolation";
        return $this->_doQuery($query, true);
    }

    // }}}
    // {{{ _doConnect()

    /**
     * do the grunt work of the connect
     *
     * @return connection on success or MDB2 Error Object on failure
     * @access protected
     */
    function _doConnect($username, $password, $persistent = false)
    {
        if (!PEAR::loadExtension($this->phptype)) {
            return $this->raiseError(MDB2_ERROR_NOT_FOUND, null, null,
                'extension '.$this->phptype.' is not compiled into PHP', __FUNCTION__);
        }

        $connection = @mysqli_init();
        if (!empty($this->dsn['charset']) && defined('MYSQLI_SET_CHARSET_NAME')) {
            @mysqli_options($connection, MYSQLI_SET_CHARSET_NAME, $this->dsn['charset']);
        }

        if ($this->options['ssl']) {
            @mysqli_ssl_set(
                $connection,
                empty($this->dsn['key'])    ? null : $this->dsn['key'],
                empty($this->dsn['cert'])   ? null : $this->dsn['cert'],
                empty($this->dsn['ca'])     ? null : $this->dsn['ca'],
                empty($this->dsn['capath']) ? null : $this->dsn['capath'],
                empty($this->dsn['cipher']) ? null : $this->dsn['cipher']
            );
        }

        if (!@mysqli_real_connect(
            $connection,
            $this->dsn['hostspec'],
            $username,
            $password,
            $this->database_name,
            $this->dsn['port'],
            $this->dsn['socket']
        )) {
            if (($err = @mysqli_connect_error()) != '') {
                return $this->raiseError(null,
                    null, null, $err, __FUNCTION__);
            } else {
                return $this->raiseError(MDB2_ERROR_CONNECT_FAILED, null, null,
                    'unable to establish a connection', __FUNCTION__);
            }
        }

        if (!empty($this->dsn['charset']) && !defined('MYSQLI_SET_CHARSET_NAME')) {
            $result = $this->setCharset($this->dsn['charset'], $connection);
            if (PEAR::isError($result)) {
                return $result;
            }
        }

        return $connection;
    }

    // }}}
    // {{{ connect()

    /**
     * Connect to the database
     *
     * @return true on success, MDB2 Error Object on failure
     */
    function connect()
    {
        if (is_object($this->connection)) {
            //if (count(array_diff($this->connected_dsn, $this->dsn)) == 0) {
            if (MDB2::areEquals($this->connected_dsn, $this->dsn)) {
                return MDB2_OK;
            }
            $this->connection = 0;
        }

        $connection = $this->_doConnect(
            $this->dsn['username'],
            $this->dsn['password']
        );
        if (PEAR::isError($connection)) {
            return $connection;
        }

        $this->connection = $connection;
        $this->connected_dsn = $this->dsn;
        $this->connected_database_name = $this->database_name;
        $this->dbsyntax = $this->dsn['dbsyntax'] ? $this->dsn['dbsyntax'] : $this->phptype;

        $this->_getServerCapabilities();

        return MDB2_OK;
    }

    // }}}
    // {{{ setCharset()

    /**
     * Set the charset on the current connection
     *
     * @param string    charset (or array(charset, collation))
     * @param resource  connection handle
     *
     * @return true on success, MDB2 Error Object on failure
     */
    function setCharset($charset, $connection = null)
    {
        if (is_null($connection)) {
            $connection = $this->getConnection();
            if (PEAR::isError($connection)) {
                return $connection;
            }
        }
        $collation = null;
        if (is_array($charset) && 2 == count($charset)) {
            $collation = array_pop($charset);
            $charset   = array_pop($charset);
        }
        $client_info = mysqli_get_client_version();
        if (OS_WINDOWS && ((40111 > $client_info) ||
            ((50000 <= $client_info) && (50006 > $client_info)))
        ) {
            $query = "SET NAMES '".mysqli_real_escape_string($connection, $charset)."'";
            if (!is_null($collation)) {
                $query .= " COLLATE '".mysqli_real_escape_string($connection, $collation)."'";
            }
            return $this->_doQuery($query, true, $connection);
        }
        if (!$result = mysqli_set_charset($connection, $charset)) {
            $err =& $this->raiseError(null, null, null,
                'Could not set client character set', __FUNCTION__);
            return $err;
        }
        return $result;
    }

    // }}}
    // {{{ databaseExists()

    /**
     * check if given database name is exists?
     *
     * @param string $name    name of the database that should be checked
     *
     * @return mixed true/false on success, a MDB2 error on failure
     * @access public
     */
    function databaseExists($name)
    {
        $connection = $this->_doConnect($this->dsn['username'],
                                        $this->dsn['password']);
        if (PEAR::isError($connection)) {
            return $connection;
        }

        $result = @mysqli_select_db($connection, $name);
        @mysqli_close($connection);

        return $result;
    }

    // }}}
    // {{{ disconnect()

    /**
     * Log out and disconnect from the database.
     *
     * @param  boolean $force if the disconnect should be forced even if the
     *                        connection is opened persistently
     * @return mixed true on success, false if not connected and error
     *                object on error
     * @access public
     */
    function disconnect($force = true)
    {
        if (is_object($this->connection)) {
            if ($this->in_transaction) {
                $dsn = $this->dsn;
                $database_name = $this->database_name;
                $persistent = $this->options['persistent'];
                $this->dsn = $this->connected_dsn;
                $this->database_name = $this->connected_database_name;
                $this->options['persistent'] = $this->opened_persistent;
                $this->rollback();
                $this->dsn = $dsn;
                $this->database_name = $database_name;
                $this->options['persistent'] = $persistent;
            }

            if ($force) {
                @mysqli_close($this->connection);
            }
        }
        return parent::disconnect($force);
    }

    // }}}
    // {{{ standaloneQuery()

   /**
     * execute a query as DBA
     *
     * @param string $query the SQL query
     * @param mixed   $types  array that contains the types of the columns in
     *                        the result set
     * @param boolean $is_manip  if the query is a manipulation query
     * @return mixed MDB2_OK on success, a MDB2 error on failure
     * @access public
     */
    function &standaloneQuery($query, $types = null, $is_manip = false)
    {
        $user = $this->options['DBA_username']? $this->options['DBA_username'] : $this->dsn['username'];
        $pass = $this->options['DBA_password']? $this->options['DBA_password'] : $this->dsn['password'];
        $connection = $this->_doConnect($user, $pass);
        if (PEAR::isError($connection)) {
            return $connection;
        }

        $offset = $this->offset;
        $limit = $this->limit;
        $this->offset = $this->limit = 0;
        $query = $this->_modifyQuery($query, $is_manip, $limit, $offset);
        
        $result =& $this->_doQuery($query, $is_manip, $connection, $this->database_name);
        if (!PEAR::isError($result)) {
            $result = $this->_affectedRows($connection, $result);
        }

        @mysqli_close($connection);
        return $result;
    }

    // }}}
    // {{{ _doQuery()

    /**
     * Execute a query
     * @param string $query  query
     * @param boolean $is_manip  if the query is a manipulation query
     * @param resource $connection
     * @param string $database_name
     * @return result or error object
     * @access protected
     */
    function &_doQuery($query, $is_manip = false, $connection = null, $database_name = null)
    {
        $this->last_query = $query;
        $result = $this->debug($query, 'query', array('is_manip' => $is_manip, 'when' => 'pre'));
        if ($result) {
            if (PEAR::isError($result)) {
                return $result;
            }
            $query = $result;
        }
        if ($this->options['disable_query']) {
            $result = $is_manip ? 0 : null;
            return $result;
        }

        if (is_null($connection)) {
            $connection = $this->getConnection();
            if (PEAR::isError($connection)) {
                return $connection;
            }
        }
        if (is_null($database_name)) {
            $database_name = $this->database_name;
        }

        if ($database_name) {
            if ($database_name != $this->connected_database_name) {
                if (!@mysqli_select_db($connection, $database_name)) {
                    $err = $this->raiseError(null, null, null,
                        'Could not select the database: '.$database_name, __FUNCTION__);
                    return $err;
                }
                $this->connected_database_name = $database_name;
            }
        }

        if ($this->options['multi_query']) {
            $result = mysqli_multi_query($connection, $query);
        } else {
            $resultmode = $this->options['result_buffering'] ? MYSQLI_USE_RESULT : MYSQLI_USE_RESULT;
            $result = mysqli_query($connection, $query);
        }

        if (!$result) {
            $err =& $this->raiseError(null, null, null,
                'Could not execute statement', __FUNCTION__);
            return $err;
        }

        if ($this->options['multi_query']) {
            if ($this->options['result_buffering']) {
                if (!($result = @mysqli_store_result($connection))) {
                    $err =& $this->raiseError(null, null, null,
                        'Could not get the first result from a multi query', __FUNCTION__);
                    return $err;
                }
            } elseif (!($result = @mysqli_use_result($connection))) {
                $err =& $this->raiseError(null, null, null,
                        'Could not get the first result from a multi query', __FUNCTION__);
                return $err;
            }
        }

        $this->debug($query, 'query', array('is_manip' => $is_manip, 'when' => 'post', 'result' => $result));
        return $result;
    }

    // }}}
    // {{{ _affectedRows()

    /**
     * Returns the number of rows affected
     *
     * @param resource $result
     * @param resource $connection
     * @return mixed MDB2 Error Object or the number of rows affected
     * @access private
     */
    function _affectedRows($connection, $result = null)
    {
        if (is_null($connection)) {
            $connection = $this->getConnection();
            if (PEAR::isError($connection)) {
                return $connection;
            }
        }
        return @mysqli_affected_rows($connection);
    }

    // }}}
    // {{{ _modifyQuery()

    /**
     * Changes a query string for various DBMS specific reasons
     *
     * @param string $query  query to modify
     * @param boolean $is_manip  if it is a DML query
     * @param integer $limit  limit the number of rows
     * @param integer $offset  start reading from given offset
     * @return string modified query
     * @access protected
     */
    function _modifyQuery($query, $is_manip, $limit, $offset)
    {
        if ($this->options['portability'] & MDB2_PORTABILITY_DELETE_COUNT) {
            // "DELETE FROM table" gives 0 affected rows in MySQL.
            // This little hack lets you know how many rows were deleted.
            if (preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $query)) {
                $query = preg_replace('/^\s*DELETE\s+FROM\s+(\S+)\s*$/',
                                      'DELETE FROM \1 WHERE 1=1', $query);
            }
        }
        if ($limit > 0
            && !preg_match('/LIMIT\s*\d(?:\s*(?:,|OFFSET)\s*\d+)?(?:[^\)]*)?$/i', $query)
        ) {
            $query = rtrim($query);
            if (substr($query, -1) == ';') {
                $query = substr($query, 0, -1);
            }

            // LIMIT doesn't always come last in the query
            // @see http://dev.mysql.com/doc/refman/5.0/en/select.html
            $after = '';
            if (preg_match('/(\s+INTO\s+(?:OUT|DUMP)FILE\s.*)$/ims', $query, $matches)) {
                $after = $matches[0];
                $query = preg_replace('/(\s+INTO\s+(?:OUT|DUMP)FILE\s.*)$/ims', '', $query);
            } elseif (preg_match('/(\s+FOR\s+UPDATE\s*)$/i', $query, $matches)) {
               $after = $matches[0];
               $query = preg_replace('/(\s+FOR\s+UPDATE\s*)$/im', '', $query);
            } elseif (preg_match('/(\s+LOCK\s+IN\s+SHARE\s+MODE\s*)$/im', $query, $matches)) {
               $after = $matches[0];
               $query = preg_replace('/(\s+LOCK\s+IN\s+SHARE\s+MODE\s*)$/im', '', $query);
            }

            if ($is_manip) {
                return $query . " LIMIT $limit" . $after;
            } else {
                return $query . " LIMIT $offset, $limit" . $after;
            }
        }
        return $query;
    }

    // }}}
    // {{{ getServerVersion()

    /**
     * return version information about the server
     *
     * @param bool   $native  determines if the raw version string should be returned
     * @return mixed array/string with version information or MDB2 error object
     * @access public
     */
    function getServerVersion($native = false)
    {
        $connection = $this->getConnection();
        if (PEAR::isError($connection)) {
            return $connection;
        }
        if ($this->connected_server_info) {
            $server_info = $this->connected_server_info;
        } else {
            $server_info = @mysqli_get_server_info($connection);
        }
        if (!$server_info) {
            return $this->raiseError(null, null, null,
                'Could not get server information', __FUNCTION__);
        }
        // cache server_info
        $this->connected_server_info = $server_info;
        if (!$native) {
            $tmp = explode('.', $server_info, 3);
            if (isset($tmp[2]) && strpos($tmp[2], '-')) {
                $tmp2 = explode('-', @$tmp[2], 2);
            } else {
                $tmp2[0] = isset($tmp[2]) ? $tmp[2] : null;
                $tmp2[1] = null;
            }
            $server_info = array(
                'major' => isset($tmp[0]) ? $tmp[0] : null,
                'minor' => isset($tmp[1]) ? $tmp[1] : null,
                'patch' => $tmp2[0],
                'extra' => $tmp2[1],
                'native' => $server_info,
            );
        }
        return $server_info;
    }

    // }}}
    // {{{ _getServerCapabilities()

    /**
     * Fetch some information about the server capabilities
     * (transactions, subselects, prepared statements, etc).
     *
     * @access private
     */
    function _getServerCapabilities()
    {
        if (!$this->server_capabilities_checked) {
            $this->server_capabilities_checked = true;

            //set defaults
            $this->supported['sub_selects'] = 'emulated';
            $this->supported['prepared_statements'] = 'emulated';
            $this->supported['triggers'] = false;
            $this->start_transaction = false;
            $this->varchar_max_length = 255;

            $server_info = $this->getServerVersion();
            if (is_array($server_info)) {
                $server_version = $server_info['major'].'.'.$server_info['minor'].'.'.$server_info['patch'];
            
                if (!version_compare($server_version, '4.1.0', '<')) {
                    $this->supported['sub_selects'] = true;
                    $this->supported['prepared_statements'] = true;
                }

                // SAVEPOINTS were introduced in MySQL 4.0.14 and 4.1.1 (InnoDB)
                if (version_compare($server_version, '4.1.0', '>=')) {
                    if (version_compare($server_version, '4.1.1', '<')) {
                        $this->supported['savepoints'] = false;
                    }
                } elseif (version_compare($server_version, '4.0.14', '<')) {
                    $this->supported['savepoints'] = false;
                }

                if (!version_compare($server_version, '4.0.11', '<')) {
                    $this->start_transaction = true;
                }

                if (!version_compare($server_version, '5.0.3', '<')) {
                    $this->varchar_max_length = 65532;
                }

                if (!version_compare($server_version, '5.0.2', '<')) {
                    $this->supported['triggers'] = true;
                }
            }
        }
    }

    // }}}
    // {{{ function _skipUserDefinedVariable($query, $position)

    /**
     * Utility method, used by prepare() to avoid misinterpreting MySQL user
     * defined variables (SELECT @x:=5) for placeholders.
     * Check if the placeholder is a false positive, i.e. if it is an user defined
     * variable instead. If so, skip it and advance the position, otherwise
     * return the current position, which is valid
     *
     * @param string $query
     * @param integer $position current string cursor position
     * @return integer $new_position
     * @access protected
     */
    function _skipUserDefinedVariable($query, $position)
    {
        $found = strpos(strrev(substr($query, 0, $position)), '@');
        if ($found === false) {
            return $position;
        }
        $pos = strlen($query) - strlen(substr($query, $position)) - $found - 1;
        $substring = substr($query, $pos, $position - $pos + 2);
        if (preg_match('/^@\w+\s*:=$/', $substring)) {
            return $position + 1; //found an user defined variable: skip it
        }
        return $position;
    }

    // }}}
    // {{{ prepare()

    /**
     * Prepares a query for multiple execution with execute().
     * With some database backends, this is emulated.
     * prepare() requires a generic query as string like
     * 'INSERT INTO numbers VALUES(?,?)' or
     * 'INSERT INTO numbers VALUES(:foo,:bar)'.
     * The ? and :name and are placeholders which can be set using
     * bindParam() and the query can be sent off using the execute() method.
     * The allowed format for :name can be set with the 'bindname_format' option.
     *
     * @param string $query the query to prepare
     * @param mixed   $types  array that contains the types of the placeholders
     * @param mixed   $result_types  array that contains the types of the columns in
     *                        the result set or MDB2_PREPARE_RESULT, if set to
     *                        MDB2_PREPARE_MANIP the query is handled as a manipulation query
     * @param mixed   $lobs   key (field) value (parameter) pair for all lob placeholders
     * @return mixed resource handle for the prepared query on success, a MDB2
     *        error on failure
     * @access public
     * @see bindParam, execute
     */
    function &prepare($query, $types = null, $result_types = null, $lobs = array())
    {
        if ($this->options['emulate_prepared']
            || $this->supported['prepared_statements'] !== true
        ) {
            $obj =& parent::prepare($query, $types, $result_types, $lobs);
            return $obj;
        }
        $is_manip = ($result_types === MDB2_PREPARE_MANIP);
        $offset = $this->offset;
        $limit = $this->limit;
        $this->offset = $this->limit = 0;
        $query = $this->_modifyQuery($query, $is_manip, $limit, $offset);
        $result = $this->debug($query, __FUNCTION__, array('is_manip' => $is_manip, 'when' => 'pre'));
        if ($result) {
            if (PEAR::isError($result)) {
                return $result;
            }
            $query = $result;
        }
        $placeholder_type_guess = $placeholder_type = null;
        $question = '?';
        $colon = ':';
        $positions = array();
        $position = 0;
        while ($position < strlen($query)) {
            $q_position = strpos($query, $question, $position);
            $c_position = strpos($query, $colon, $position);
            if ($q_position && $c_position) {
                $p_position = min($q_position, $c_position);
            } elseif ($q_position) {
                $p_position = $q_position;
            } elseif ($c_position) {
                $p_position = $c_position;
            } else {
                break;
            }
            if (is_null($placeholder_type)) {
                $placeholder_type_guess = $query[$p_position];
            }
            
            $new_pos = $this->_skipDelimitedStrings($query, $position, $p_position);
            if (PEAR::isError($new_pos)) {
                return $new_pos;
            }
            if ($new_pos != $position) {
                $position = $new_pos;
                continue; //evaluate again starting from the new position
            }
            
            //make sure this is not part of an user defined variable
            $new_pos = $this->_skipUserDefinedVariable($query, $position);
            if ($new_pos != $position) {
                $position = $new_pos;
                continue; //evaluate again starting from the new position
            }

            if ($query[$position] == $placeholder_type_guess) {
                if (is_null($placeholder_type)) {
                    $placeholder_type = $query[$p_position];
                    $question = $colon = $placeholder_type;
                }
                if ($placeholder_type == ':') {
                    $regexp = '/^.{'.($position+1).'}('.$this->options['bindname_format'].').*$/s';
                    $parameter = preg_replace($regexp, '\\1', $query);
                    if ($parameter === '') {
                        $err =& $this->raiseError(MDB2_ERROR_SYNTAX, null, null,
                            'named parameter name must match "bindname_format" option', __FUNCTION__);
                        return $err;
                    }
                    $positions[$p_position] = $parameter;
                    $query = substr_replace($query, '?', $position, strlen($parameter)+1);
                } else {
                    $positions[$p_position] = count($positions);
                }
                $position = $p_position + 1;
            } else {
                $position = $p_position;
            }
        }
        $connection = $this->getConnection();
        if (PEAR::isError($connection)) {
            return $connection;
        }

        if (!$is_manip) {
            static $prep_statement_counter = 1;
            $statement_name = sprintf($this->options['statement_format'], $this->phptype, $prep_statement_counter++ . sha1(microtime() + mt_rand()));
            $statement_name = substr(strtolower($statement_name), 0, $this->options['max_identifiers_length']);
            $query = "PREPARE $statement_name FROM ".$this->quote($query, 'text');

            $statement =& $this->_doQuery($query, true, $connection);
            if (PEAR::isError($statement)) {
                return $statement;
            }
            $statement = $statement_name;
        } else {
            $statement = @mysqli_prepare($connection, $query);
            if (!$statement) {
                $err =& $this->raiseError(null, null, null,
                    'Unable to create prepared statement handle', __FUNCTION__);
                return $err;
            }
        }

        $class_name = 'MDB2_Statement_'.$this->phptype;
        $obj = new $class_name($this, $statement, $positions, $query, $types, $result_types, $is_manip, $limit, $offset);
        $this->debug($query, __FUNCTION__, array('is_manip' => $is_manip, 'when' => 'post', 'result' => $obj));
        return $obj;
    }

    // }}}
    // {{{ replace()

    /**
     * Execute a SQL REPLACE query. A REPLACE query is identical to a INSERT
     * query, except that if there is already a row in the table with the same
     * key field values, the REPLACE query just updates its values instead of
     * inserting a new row.
     *
     * The REPLACE type of query does not make part of the SQL standards. Since
     * practically only MySQL implements it natively, this type of query is
     * emulated through this method for other DBMS using standard types of
     * queries inside a transaction to assure the atomicity of the operation.
     *
     * @access public
     *
     * @param string $table name of the table on which the REPLACE query will
     *  be executed.
     * @param array $fields associative array that describes the fields and the
     *  values that will be inserted or updated in the specified table. The
     *  indexes of the array are the names of all the fields of the table. The
     *  values of the array are also associative arrays that describe the
     *  values and other properties of the table fields.
     *
     *  Here follows a list of field properties that need to be specified:
     *
     *    value:
     *          Value to be assigned to the specified field. This value may be
     *          of specified in database independent type format as this
     *          function can perform the necessary datatype conversions.
     *
     *    Default:
     *          this property is required unless the Null property
     *          is set to 1.
     *
     *    type
     *          Name of the type of the field. Currently, all types Metabase
     *          are supported except for clob and blob.
     *
     *    Default: no type conversion
     *
     *    null
     *          Boolean property that indicates that the value for this field
     *          should be set to null.
     *
     *          The default value for fields missing in INSERT queries may be
     *          specified the definition of a table. Often, the default value
     *          is already null, but since the REPLACE may be emulated using
     *          an UPDATE query, make sure that all fields of the table are
     *          listed in this function argument array.
     *
     *    Default: 0
     *
     *    key
     *          Boolean property that indicates that this field should be
     *          handled as a primary key or at least as part of the compound
     *          unique index of the table that will determine the row that will
     *          updated if it exists or inserted a new row otherwise.
     *
     *          This function will fail if no key field is specified or if the
     *          value of a key field is set to null because fields that are
     *          part of unique index they may not be null.
     *
     *    Default: 0
     *
     * @return mixed MDB2_OK on success, a MDB2 error on failure
     */
    function replace($table, $fields)
    {
        $count = count($fields);
        $query = $values = '';
        $keys = $colnum = 0;
        for (reset($fields); $colnum < $count; next($fields), $colnum++) {
            $name = key($fields);
            if ($colnum > 0) {
                $query .= ',';
                $values.= ',';
            }
            $query.= $this->quoteIdentifier($name, true);
            if (isset($fields[$name]['null']) && $fields[$name]['null']) {
                $value = 'NULL';
            } else {
                $type = isset($fields[$name]['type']) ? $fields[$name]['type'] : null;
                $value = $this->quote($fields[$name]['value'], $type);
                if (PEAR::isError($value)) {
                    return $value;
                }
            }
            $values.= $value;
            if (isset($fields[$name]['key']) && $fields[$name]['key']) {
                if ($value === 'NULL') {
                    return $this->raiseError(MDB2_ERROR_CANNOT_REPLACE, null, null,
                        'key value '.$name.' may not be NULL', __FUNCTION__);
                }
                $keys++;
            }
        }
        if ($keys == 0) {
            return $this->raiseError(MDB2_ERROR_CANNOT_REPLACE, null, null,
                'not specified which fields are keys', __FUNCTION__);
        }

        $connection = $this->getConnection();
        if (PEAR::isError($connection)) {
            return $connection;
        }

        $table = $this->quoteIdentifier($table, true);
        $query = "REPLACE INTO $table ($query) VALUES ($values)";
        $result =& $this->_doQuery($query, true, $connection);
        if (PEAR::isError($result)) {
            return $result;
        }
        return $this->_affectedRows($connection, $result);
    }

    // }}}
    // {{{ nextID()

    /**
     * Returns the next free id of a sequence
     *
     * @param string $seq_name name of the sequence
     * @param boolean $ondemand when true the sequence is
     *                          automatic created, if it
     *                          not exists
     *
     * @return mixed MDB2 Error Object or id
     * @access public
     */
    function nextID($seq_name, $ondemand = true)
    {
        $sequence_name = $this->quoteIdentifier($this->getSequenceName($seq_name), true);
        $seqcol_name = $this->quoteIdentifier($this->options['seqcol_name'], true);
        $query = "INSERT INTO $sequence_name ($seqcol_name) VALUES (NULL)";
        $this->pushErrorHandling(PEAR_ERROR_RETURN);
        $this->expectError(MDB2_ERROR_NOSUCHTABLE);
        $result =& $this->_doQuery($query, true);
        $this->popExpect();
        $this->popErrorHandling();
        if (PEAR::isError($result)) {
            if ($ondemand && $result->getCode() == MDB2_ERROR_NOSUCHTABLE) {
                $this->loadModule('Manager', null, true);
                $result = $this->manager->createSequence($seq_name);
                if (PEAR::isError($result)) {
                    return $this->raiseError($result, null, null,
                        'on demand sequence '.$seq_name.' could not be created', __FUNCTION__);
                } else {
                    return $this->nextID($seq_name, false);
                }
            }
            return $result;
        }
        $value = $this->lastInsertID();
        if (is_numeric($value)) {
            $query = "DELETE FROM $sequence_name WHERE $seqcol_name < $value";
            $result =& $t…