From: chester c young <chestercyoung@yahoo.com>
To: Randall Lucas <rlucas@tercent.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: UNIQUE boolean: only one row may be "true"
Date: Tue, 6 May 2003 10:26:04 -0700 (PDT)
Message-ID: <20030506172604.92026.qmail@web12708.mail.yahoo.com> (raw)
In-Reply-To: <FA25F27B-7FDB-11D7-A71E-000A957653D6@tercent.net>
> How shall I create a constraint such that only one row may be 'true'?
Instead of, or along with your pg boolean, use a C type boolean where
true is 1 and false is null:
...
col_tf int check( col_tf = 1 || col_tf is null ) unique,
...
a kludge to be sure, but works
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To: pgsql-sql@postgresql.org
Cc: chestercyoung@yahoo.com, rlucas@tercent.net
Subject: Re: UNIQUE boolean: only one row may be "true"
In-Reply-To: <20030506172604.92026.qmail@web12708.mail.yahoo.com>
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