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From: Josh Berkus <josh@agliodbs.com>
Reply-To: josh@agliodbs.com
Organization: Aglio Database Solutions
To: Robert Treat <rtreat@webmd.net>, pgsql-sql@postgresql.org
Subject: Re: help with "delete joins"
Date: Mon, 30 Jun 2003 17:35:29 -0700
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Robert,

> delete * from foo where not (foo.a =3D bar.a and foo.b=3Dbar.b and
> foo.c=3Dbar.c) ;
>=20
> so i end up with=20
>=20
> postgres=3D# select * from foo;=20
>  a | b | c | d=20
> ---+---+---+---
>  1 | 2 | 4 | A
>  4 | 5 | 6 | b
> (2 rows)
>=20
> but thats not valid sql, is there some way to accomplish this?=20

Um, your example result doesn't match your pseudo-query.  Assuming that you=
=20
want to delete everything that DOES match, not everything that DOESN'T, do:

DELETE FROM foo=20
WHERE EXISTS ( SELECT bar.a FROM bar
	WHERE bar.a =3D foo.a AND bar.b =3D foo.b
		AND bar.c =3D foo.c );


--=20
-Josh Berkus
 Aglio Database Solutions
 San Francisco