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Editorial Team
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Asked: 2026-05-13T15:12:06+00:00

I got this code, I would like to optimize. I basically can add new

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I got this code, I would like to optimize.
I basically can add new columns to “Disp” table later on, and I don’t want to come back modify this function.
I cannot use dynamic SQL. Right? Is there anything else that would work in my case?

This is the function:

ALTER FUNCTION [GetDate] 
(@hdrnumber INT, @DateColName VARCHAR(50))
RETURNS DATETIME
AS
BEGIN
    DECLARE @dt DATETIME
        SELECT  @dt = CASE
          WHEN @DateColName = 'ord_bookdate' THEN [ord_bookdate]
          WHEN @DateColName = 'ord_startdate' THEN [ord_startdate]
          WHEN @DateColName = 'ord_completiondate' THEN [ord_completiondate]
          WHEN @DateColName = 'pack_date_from' THEN [pack_date_from]
          WHEN @DateColName = 'pack_date_to' THEN [pack_date_to]
         END
        FROM    [Disp]
        WHERE   [hdrnumber] = @hdrnumber

    RETURN @dt
END

(removed some of the code, because it’s a long one, but hopefully what I left in here will make sense to you guys)

how do i use this function?
well it basically looks like this:

 insert into tablename (...)
 select somedate, [GetDate](somedate, somecolumn)
 from sometable
 where 1 = 1
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1 Answer

  1. Editorial Team

    You either need to use dynamic sql which you can’t do within a user-defined function (so you’d need to remove it out of the function), or like you are doing with a CASE statement (which isn’t fully generic).

    I think I’d personally go with the CASE approach to start with and consider dynamic sql if proves to give better performance (maybe with a larger number of different possible fields).
    You would have some maintenance work to do to keep the CASE up to date, but I can’t imagine more fields would be added that often?

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