X-Original-To: pgsql-sql-postgresql.org@localhost.postgresql.org
Received: from localhost (unknown [200.46.204.144])
	by svr1.postgresql.org (Postfix) with ESMTP id D0CF5D1B170
	for <pgsql-sql-postgresql.org@localhost.postgresql.org>;
	Mon, 28 Jun 2004 19:28:09 -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 64551-05
	for <pgsql-sql-postgresql.org@localhost.postgresql.org>;
	Mon, 28 Jun 2004 22:28:10 +0000 (GMT)
Received: from lithium.sunwave.net (lithium.sunwave.net [64.141.16.21])
	by svr1.postgresql.org (Postfix) with ESMTP id 718D8D1B191
	for <pgsql-sql@postgresql.org>; Mon, 28 Jun 2004 19:28:06 -0300 (ADT)
Received: from localhost (localhost [127.0.0.1])
	by lithium.sunwave.net (Postfix) with ESMTP
	id DCFB844300; Mon, 28 Jun 2004 15:28:08 -0700 (PDT)
Received: from lithium.sunwave.net ([127.0.0.1])
	by localhost (lithium.sunwave.net [127.0.0.1]) (amavisd-new, port 10024)
	with LMTP id 17699-01-50; Mon, 28 Jun 2004 15:28:08 -0700 (PDT)
Received: from starbucks.in.sunwave.net (fw1-et-1.sunwave.net [64.141.16.15])
	by lithium.sunwave.net (Postfix) with ESMTP
	id A6ED5441C0; Mon, 28 Jun 2004 15:28:08 -0700 (PDT)
From: Michael A Nachbaur <mike@nachbaur.com>
To: Stefan Weiss <spaceman@foo.at>
Subject: Re: "=" operator vs. "IS"
Date: Mon, 28 Jun 2004 15:28:08 -0700
User-Agent: KMail/1.6.1
Cc: pgsql-sql@postgresql.org
References: <200406290002.29099.spaceman@foo.at>
In-Reply-To: <200406290002.29099.spaceman@foo.at>
MIME-Version: 1.0
Content-Disposition: inline
Content-Type: text/plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Message-Id: <200406281528.08526.mike@nachbaur.com>
X-Virus-Scanned: by amavisd-new at hub.org
X-Spam-Status: No, hits=0.0 tagged_above=0.0 required=5.0 tests=
X-Spam-Level: 
X-Archive-Number: 200406/281
X-Sequence-Number: 18226

On June 28, 2004 03:02 pm, Stefan Weiss wrote:
> I'm just curious - why is it not possible to use the "=" operator to
> compare values with NULL? I suspect that the SQL standard specified
> it that way, but I can't see any ambiguity in an expression like "AND
> foo.bar = NULL". Is it because NULL does not "equal" any value, and the
> expression should be read as "foo.bar is unknown"? Or is there something
> else I'm missing?

As far as I have been able to tell, it is one of those quirks about SQL that 
you shouldn't bother trying to understand.  It just IS.  <rimshot/>

-- 
Michael A. Nachbaur <mike@nachbaur.com>
http://nachbaur.com/pgpkey.asc