updating the modified time

updating modified time.
        $this->Editor->setConfig('afterEditFun', array(
            &$this,
            'updateModifiedTime'
        ));

and

    function updateModifiedTime($id, $col, $info)
    {
        $mt     = date('Y-m-d H:i:s');
        $query  = "update " . tblMain . " set modified_at = '" . $mt . "' where id = '" . $col . "' ";
        $result = $this->Editor->doQuery($query);
    }