On Thu, Jan 13, 2005 at 09:01:08 -0500,
Dave Smith <dave(dot)smith(at)candata(dot)com> wrote:
> I am trying to add a unique constraint on a column that can be null. The
> documentation states that null is treated as non equal values but I want
> them to be equal. Is there another way of doing this other than writing
> a before insert trigger?
I think you will need an after trigger to enforce that.
You might also consider using some other value than NULL. If other tables
are going to reference this one using the unique column, potentially having
a NULL could be a problem.