How to use a case statement in scalar valued function in SQL?

Question

I want to get one value from a function using a case statement. I tried the following but it does not work:

CREATE FUNCTION [FATMS].[fnReturnByPeriod]
(

            


        

Answer 1

Here's a SET based approach to write your function in SQL Server 2008

CREATE FUNCTION [FATMS].[fnReturnByPeriod]
(
    @Period INT
)
RETURNS int
AS
BEGIN
    return isnull((SELECT min(v)
    from (values
     (1,1),
     (7,2),
     (30,3),
     (90,4),
     (180,5),
     (360,6)) t(n,v)
    where n >= @Period and @period>0), 0)
END

The way you have written it, all the CASE branches return 1, so you might as well use

return case when @period between 1 and 360 then 1 else 0 end