/**
  * Sets modifying query and performs it, IF NOT in dry run mode.
  * If in dry run mode, returns true
  * @access private
  *
  * @param  string  $sql
  * @return boolean
  */
 function _doQuery($sql)
 {
     if ($this->_dryRun) {
         return true;
     } else {
         $this->_db->SetQuery($sql);
         return $this->_db->query();
     }
 }