X-Original-To: pgsql-sql-postgresql.org@localhost.postgresql.org
Received: from localhost (av.hub.org [200.46.204.144])
	by svr1.postgresql.org (Postfix) with ESMTP id 1AAEAD7CB0
	for <pgsql-sql-postgresql.org@localhost.postgresql.org>;
	Wed,  7 Sep 2005 18:54:30 -0300 (ADT)
Received: from svr1.postgresql.org ([200.46.204.71])
	by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024)
	with ESMTP id 59587-06
	for <pgsql-sql-postgresql.org@localhost.postgresql.org>;
	Wed,  7 Sep 2005 21:54:24 +0000 (GMT)
Received: from hotmail.com (bay101-f10.bay101.hotmail.com [64.4.56.20])
	by svr1.postgresql.org (Postfix) with ESMTP id 7C718D7B95
	for <pgsql-sql@postgresql.org>; Wed,  7 Sep 2005 18:54:24 -0300 (ADT)
Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC;
	Wed, 7 Sep 2005 14:54:25 -0700
Message-ID: <BAY101-F10FD61CD14D1A8A22D9D04FCA60@phx.gbl>
Received: from 64.4.56.200 by by101fd.bay101.hotmail.msn.com with HTTP;
	Wed, 07 Sep 2005 21:54:24 GMT
X-Originating-IP: [64.4.56.200]
X-Originating-Email: [x_download@hotmail.com]
X-Sender: x_download@hotmail.com
In-Reply-To: <20050906144541.GA30161@wolff.to>
From: "DownLoad X" <x_download@hotmail.com>
To: bruno@wolff.to
Cc: pgsql-sql@postgresql.org
Subject: Re: Searching for results with an unknown amount of data
Date: Wed, 07 Sep 2005 22:54:24 +0100
Mime-Version: 1.0
Content-Type: text/plain; format=flowed
X-OriginalArrivalTime: 07 Sep 2005 21:54:25.0165 (UTC)
	FILETIME=[B64B6BD0:01C5B3F6]
X-Virus-Scanned: by amavisd-new at hub.org
X-Spam-Status: No, hits=2.915 required=5 tests=[AWL=-0.666,
	DNS_FROM_RFC_ABUSE=0.374, DNS_FROM_RFC_POST=1.376,
	MSGID_FROM_MTA_HEADER=0, RCVD_IN_BL_SPAMCOP_NET=1.832]
X-Spam-Level: **
X-Archive-Number: 200509/80
X-Sequence-Number: 22627



> > Now, I want to find all objects that have at most properties 1,2,3, say 
>(so
> > something with (1,2) is okay, as is (1,2,3)). I can't see a way to do 
>this
> > -- can anyone help?
>
>It sounds like you are trying to find all objects that do not have any
>properties outside of a specific list. One way to get that list is:

That's exactly right.

>
>SELECT a_id
>   FROM a
>     WHERE
>       NOT EXISTS
>         (SELECT 1
>           FROM b
>           WHERE
>             b.a_id = a.a_id
>             AND
>             b.property NOT IN (1, 2, 3)
>         )
>;

Yupp, this appears to do it! The 'double negation' is very clever.

Thanks a lot,
DL