public function isValid($value) { $isValid = true; $valueString = (string) $value; $this->_setValue($valueString); $tbl = new DbTable_Account(); $Account = Service_Auth::getAccount(); $select = $tbl->select()->where('username = ?', $Account->username); $select->where('password = ?', md5($value)); $row = $tbl->fetchRow($select); if ($row === null) { $isValid = false; $this->_error(self::UNKNOWN); } return $isValid; }