Config Extend to Database

class MY_Config extends CI_Config {

/**
 * CodeIgniter Config Extended Library
 *
 * This class extends the config to a database
 *
 * @package        CodeIgniter
 * @subpackage    Extended Libraries
 * @category    Extended Libraries
 * @author        Tim Wood (aka codearachnid)
 * @link        http://www.codearachnid.com/ci/db_fetch
 * 
 * you must have the following structure setup in order to use this class
 * 
    CREATE TABLE IF NOT EXISTS `site_config` (
      `config_id` int(11) NOT NULL auto_increment,
      `last_updated` timestamp NOT NULL default '0000-00-00 00:00:00' on update CURRENT_TIMESTAMP,
      `config_key` varchar(60) NOT NULL,
      `config_value` longtext NOT NULL,
      PRIMARY KEY  (`config_id`)
    ) ENGINE=MyISAM;
 * 
 * 
 */

    function MY_Config()
    {
        parent::CI_Config();
    }
    
    function db_config_fetch()
    {
        $CI =& get_instance();
        $query = $CI->db->get($this->item('dbt_site_config'));
        
        foreach ($query->result() as $row)
        {
            $this->set_item($row->config_key, $row->config_value);
        }
        
    }
    
}
?>

$this->config->db_config_fetch();

$config['dbt_site_config']        = 'site_config';