Hi

>It is not heavy, you only need stored procedure with input and output parameters
>
>Something very simple
>

>CREATE PROCEDURE TEST_PROC (
>    IN_1 DOUBLE PRECISION,
>    IN_2 DOUBLE PRECISION)
>RETURNS (
>    OUT_1 DOUBLE PRECISION)
>AS
>begin
>    out_1 = case
>               when ( in_1 > in_2 ) then in_1 - in_2
>               when ( in_1 is null or in_2 is null) then 0
>               else 0 end ;
>  /* Procedure Text */
>  suspend;
>end
>

That is it and I use it as SELECT TestProc(t.Var1, t.Var2) AS MyFldName,....?

Thanks a lot for the precise code.