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Re: Adding a conditional unique constraint

From: Phillip Smith <phillip(dot)smith(at)weatherbeeta(dot)com(dot)au>
To: Nathaniel <naptrel(at)yahoo(dot)co(dot)uk>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: Adding a conditional unique constraint
Date: 2007-04-19 11:51:26
Message-ID: 1176983487.4698.2.camel@fukawi2.homelinux.net (view raw or flat)
Thread:
Lists: pgsql-novice
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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Subject: Re: Adding a conditional unique constraint
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