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

Stephane Bortzmeyer <bortzmeyer@nic.fr> writes:
> Yes, PostgreSQL is right and implement the standard. Now, what's the
> rationale for the standard? I understand it for a single column but,
> for several columns, it should be still possible to have different
> tuples, such as (3, NULL) and (5, NULL) for instance.

If that's what you want, declare it as UNIQUE not PRIMARY KEY.

            regards, tom lane