Re: PRIMARY KEY on a *group* of columns imply that each column is NOT

On Wed, Apr 27, 2005 at 05:19:32AM +0000,
Patrick TJ McPhee <ptjm(at)interlog(dot)com> wrote
a message of 37 lines which said:

> but you should know that in SQL, unique constraints don't apply to
> rows containing null values

May be I should but I didn't.

> your table definition will be as you want it, but the constraint you
> want won't be there.

OK, I will try to write a custom trigger, then.