foreach($this->add_fields as $k => $v) {
                    if(isset($dv[$k]))    $s .= ", `".$this->fields[$v]."` = \"".$this->db->escape($dv[$k])."\" ";
                    else                $s .= ", `".$this->fields[$v]."` = `".$this->fields[$v]."` ";
                }