This is really good stuff. Thank you all for being so helpful

Brilliant

If only I would have known all this before. Probably would have saved some hair

Rahah! I've got it. Get rid of NULL and do 0x00

CREATE PROCEDURE SampleProc

@a uniqueidentifier,

@b-2 uniqueidentifier,

@c uniqueidentifier

AS

-- convert NULL parameters to 'empty' values

-- NULLs cannot be correctly compared using this pattern

SET...