on 10/8/05 11:36 PM, mileskeaton@xxxxxxxxx purportedly said: > I know it's tempting to say, "just link a separate table for the book > and don't store the book name" but let's just pretend that's not an > option - because I'm not actually dealing with books : I just made up > this simplified version of something at work, where we can't change > the table : both isbn and name MUST be in the table, and what I'm > trying to do is put a CONSTRAINT on the table definition to protect > against user error, by making sure that any entered isbn is only tied > to one book-name in that table. I would create a multi-column unique index on the table. This should solve the problem mentioned although you may still have an integrity issue if a "book" name is mistyped. Best regards, Keary Suska Esoteritech, Inc. "Demystifying technology for your home or business" ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq