By golly you're right; maybe I should try this stuff before I email hundreds of people :) On Wed, May 12, 2010 at 12:00 AM, Thom Brown <thombrown@xxxxxxxxx> wrote: > On 12 May 2010 07:34, Mike Christensen <mike@xxxxxxxxxxxxx> wrote: >> >> I have the following constraint which almost works: >> >> ALTER TABLE ingredientforms ADD CONSTRAINT >> ingredientforms_UniqueIngredientForm UNIQUE(IngredientId, >> FormDisplayName); >> >> However, I want to allow rows that have the same IngredientId >> FormDisplayName /iff/ FormDisplayName is null. If FormDisplayName is >> not null, then it must be unique. >> >> 1, NULL >> 1, NULL >> >> Would be allowed. >> >> 1, 'Foo' >> 1, 'Foo' >> >> would violate the constraint. >> >> 1, 'Foo' >> 1, 'Bar' >> >> would be allowed. >> >> Any way to do this? Insert performance is not an issue since the >> table is almost never changed.. >> >> Mike >> > > What you've said you want to do looks like what you'd be allowed to do > anyway. You're allowed duplicate values on a unique constraint if one of > the columns is null. > Regards > Thom > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
