stored procedure functions not working properly? - stored-procedures

Question

i am writing a procedure function in phpmyadmin for attendance purpose.But i am getting wrong information from function if condition.
below is the sample code for procedure and functions without if.
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `USP_GetEmployeeAttendanceReport`(IN selectedIndex int,IN searchText nvarchar(20),IN selectedDate datetime)
BEGIN
select FN_CheckEmpAttendanceStatus(selectedIndex,selectedDate);
END
Function FN_CheckEmpAttendanceStatus
DELIMITER $$
CREATE DEFINER=`root`#`localhost` FUNCTION `FN_CheckEmpAttendanceStatus`(cardid varchar(150),selectedDate datetime) RETURNS int(11)
BEGIN
DECLARE result INT;
set result=(select count(*) from iotrans where CARDID=cardid and dt=selectedDate);
return result;
END
but from function i am getting garbage values (i.e 80,0,81,82....).thanks in advance

Answer 1

The problem is most likely caused by the fact that you use the same name cardid for a function parameter as for a column in iotrans, thus MySQL can't tell them apart and condition WHERE CARDID=cardid always evaluates as TRUE.
Always give distinct names to routine parameters. I'd suggest to come up with some naming scheme, e.g. putting a underscore in front of the name of a parameter, so that you do that consistently across all your code and can easily tell whether it's a parameter or a column name.
One more thing usage of result variable is unnecessary overhead in your case as is BEGIN...END block.
That being said your function might've looked like this
CREATE DEFINER=`root`#`localhost`
FUNCTION FN_CheckEmpAttendanceStatus
(
_cardid varchar(150),
_selectedDate datetime
) RETURNS INT(11)
RETURN
(
SELECT COUNT(*)
FROM iotrans
WHERE cardid = _cardid
AND dt = _selectedDate
);