Alban Hertroys <alban@xxxxxxxxxxxxxxxxx> writes: > Ottavio Campana wrote: >> What I want to do is a function inserting a new item into the table >> ensuring that there is only one record in the table having a particular >> description and at the same time the active field set to true (it might >> seem stupid, but the application requires it). > Assuming active can't be NULL, what's wrong with a UNIQUE constraint on > (description, active)? I think he does not want descriptions to be unique among non-active entries. If so, the right thing is a partial unique index: CREATE UNIQUE INDEX ... on (description) WHERE active; regards, tom lane
