On Wed, Apr 27, 2005 at 04:50:23PM +0200, Sebastian Böck <sebastianboeck@xxxxxxxxxx> wrote a message of 48 lines which said: > CREATE UNIQUE INDEX na ON x (name, address) WHERE address IS NULL; No, because it prevents two tuples with the same value of "name". ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq