Re: multi-column unique constraints with nullable columns

>I believe you can add partial unique indexes to cover the case where a
>column is null, but if you have multiple nullable columns you need to
>worry about you end up with a bunch of indexes.

Hmmm. I hadn't thought of that, thanks. Yes, the indexes would be unnessecary though. Speaking of, should be concerned
aboutindexing NULLABLE columns? 

> Also, is this in compliance with SQL92? I'm surprised constraints work
> this way.
he
I read that. I think you're right, it sounds like any comparison containing NULL at all will fail.


I wrote the following procedure, which seems to do the trick. I guess my plan would be to write a bunch of these, and
createthe indexes manually. If anyone sees any problems with this, I'd love some input. Also, if anyone at the end of
thisemail is a DBA/Consultant type and works in the San Diego area... Definitely let me know :) 

CREATE FUNCTION check_mytable_natkey() RETURNS opaque AS 'DECLARE conflictingpk integer;BEGIN
  SELECT INTO conflictingpk a    FROM mytable    WHERE ((b is null and NEW.b is null) or b = NEW.b)      AND ((c is
nulland NEW.c is null) or c = NEW.c); 
  IF FOUND THEN     RAISE EXCEPTION ''Invalid Row!'';  END IF;    RETURN NEW;END;
'LANGUAGE 'plpgsql';