Question

Sorry to be a bother guys. I have been tasked with some code review at a client location and the laptop issued to me does not have SQL installed. While I am waiting for the installation to happen, wanted to get busy looking at the code and came across this gem

CREATE FUNCTION [dbo].[Uf_GetTotalDaysInMonth]
(
    -- Add the parameters for the function here
    @anydateofMonth datetime
)
RETURNS int
AS
BEGIN
    -- Declare the return variable here
    DECLARE @totalDaysInMonth int
    -- Add the T-SQL statements to compute the return value here

        DECLARE @givendate datetime
        SET @givendate = STR(Year(@givendate)) + '-' + STR(Month(@givendate) + 1) + '-01' 

        select @totalDaysInMonth = datepart(dd, dateadd(day, -1, @givendate))

    -- Return the result of the function
    RETURN @totalDaysInMonth

END

Ignoring the use of needless extra variable, I believe that this function will crash in December

STR(Month(@givendate) + 1)

will evaluate to 13 and will give an out of scope date error. Could someone please validate this for me?

Answer 1

You vill get error in your function when pass @anydateofMonth December date.
You can use this:

CREATE FUNCTION [dbo].[Uf_GetTotalDaysInMonth]
(
    -- Add the parameters for the function here
    @anydateofMonth datetime
)
RETURNS int
AS
 BEGIN
    DECLARE @nextMonth datetime
    SET @nextMonth = dateadd(m, 1, @anydateofMonth)
    RETURN (SELECT Day(dateadd(d, -Day(@nextMonth), @nextMonth)))
  END