我的php和mysql代码有什么问题？

Question

好吧，这是我的代码，我使用codeigniter，但是总是说错误...

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package     CodeIgniter
 * @author      ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license     http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since       Version 1.0
 * @filesource
 */

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

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

    var $dbdriver = 'mysql';

    // The character used for escaping
    var $_escape_char = '`';

    // clause and character used for LIKE escape sequences - not used in MySQL
    var $_like_escape_str = '';
    var $_like_escape_chr = '';

    /**
     * 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 $delete_hack = TRUE;

    /**
     * The syntax to count rows is slightly different across different
     * database engines, so this string appears in each driver and is
     * used for the count_all() and count_all_results() functions.
     */
    var $_count_string = 'SELECT COUNT(*) AS ';
    var $_random_keyword = ' RAND()'; // database specific random keyword

    // whether SET NAMES must be used to set the character set
    var $use_set_names;

    /**
     * Non-persistent database connection
     *
     * @access  private called by the base class
     * @return  resource
     */
    function db_connect()
    {
        if ($this->port != '')
        {
            $this->hostname .= ':'.$this->port;
        }

        return @mysqli_connect($this->hostname, $this->username, $this->password, TRUE);
    }

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

    /**
     * Persistent database connection
     *
     * @access  private called by the base class
     * @return  resource
     */
    function db_pconnect()
    {
        if ($this->port != '')
        {
            $this->hostname .= ':'.$this->port;
        }

        return @mysqli_pconnect($this->hostname, $this->username, $this->password);
    }