From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dan Langille <dan@langille.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: DELETE FROM t WHERE EXISTS
Date: Fri, 28 Feb 2003 15:11:53 -0500
Message-ID: <5999.1046463113@sss.pgh.pa.us> (raw)
In-Reply-To: <3E5F530B.1649.424D34C1@localhost>
References: <3E5F530B.1649.424D34C1@localhost>
"Dan Langille" <dan@langille.org> writes:
> So I tried this:
> DELETE FROM clp
> WHERE NOT EXISTS (
> SELECT *
> FROM clp
> ORDER BY commit_date
> LIMIT 100);
> Uhh uhh, nothing deleted. I don't understand why.
Because the inner SELECT is a constant: you forgot to make it depend on
the current outer row. So EXISTS succeeds at every row, unless clp is
already empty.
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, dan@langille.org
Subject: Re: DELETE FROM t WHERE EXISTS
In-Reply-To: <5999.1046463113@sss.pgh.pa.us>
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