Thanks for your help opc.three.

One last thing: I hate to leave less than optimal code out there for posterity so here is my last, optimized function with all string manipulation removed 🙂

CREATE FUNCTION makeGUID

(

@GUID AS UNIQUEIDENTIFIER,

@number AS BIGINT

)

RETURNS UNIQUEIDENTIFIER

AS

BEGIN

RETURN CAST(CAST(@guid AS BINARY(10)) + CAST(@Number AS BINARY(6)) AS UNIQUEIDENTIFIER)

END

GO