MySQL function is returning wrong value

Question

I have a function with 4 parameters and for example if I set null/empty value for the first parameter which is type DATE I get the result 2 instead of 1.

SET @p0=''; SET @p1=''; SET @p2=''; SET @p3=''; SELECT `MY_FN`(@p0, @p1, @p2, @p3) AS `MY_FN`;

My code:

BEGIN
 IF PARAM1_DATE IS NULL or PARAM1_DATE='' THEN 
 SET @STATUS = 1;
 ELSE 
 SET @STATUS = 2;
 END IF;
 
 
 RETURN @STATUS;
END

I've tried also ISNULL(NULLIF(PARAM1_DATE,'') same result

• P.Salmon: Go on add rest of function..

Answer 1

the validation of parameters OCCURS BEFORE function code is executed you need to make sure a valid date (if that's what param1_date datatype is) is passed in the call to the function. if you want to pass any old rubbish then define as char and test in function..