Re: Adding a conditional unique constraint

ALTER TABLE proposals
ADD CONSTRAINT one_draft_each
CHECK (draft IS false)
OR (draft IS true AND user_id NOT IN (SELECT user_id FROM proposals
WHERE draft IS true))

It will be a lot slower than a UNIQUE constraint, especially as your
table gets bigger...

On Thu, 2007-04-19 at 10:52 +0100, Nathaniel wrote:

> ALTER TABLE proposals ADD CONSTRAINT one_draft_each CHECK draft IS
> false OR UNIQUE user_id

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