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 CC980D1B1BE for ; Tue, 29 Jun 2004 13:28:00 -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 71668-05 for ; Tue, 29 Jun 2004 16:27:53 +0000 (GMT) Received: from mail.gmx.net (pop.gmx.net [213.165.64.20]) by svr1.postgresql.org (Postfix) with SMTP id B285DD1B1AA for ; Tue, 29 Jun 2004 13:27:50 -0300 (ADT) Received: (qmail 15638 invoked by uid 65534); 29 Jun 2004 16:27:49 -0000 Received: from dsl-213-023-250-211.arcor-ip.net (EHLO colt.pezone.net) (213.23.250.211) by mail.gmx.net (mp023) with SMTP; 29 Jun 2004 18:27:49 +0200 X-Authenticated: #495269 From: Peter Eisentraut To: Rich Hall , pgsql-sql@postgresql.org Subject: Re: FW: "=" operator vs. "IS" Date: Tue, 29 Jun 2004 18:27:48 +0200 User-Agent: KMail/1.5.1 References: <7A4ADADFC8AFF0478D47F63BEDD57CE33A320C@gpmail.gphq.genpathpharma.com> <40E17C81.3090308@micropat.com> In-Reply-To: <40E17C81.3090308@micropat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200406291827.48502.peter_e@gmx.net> 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: 200406/294 X-Sequence-Number: 18239 Rich Hall wrote: > My question is why is the form > > "(anything) = NULL" > > allowed? > > Since > > "(anything) = NULL" is always Null, this cannot be what the coder > intended. Using that same line of argument, why is 1+1 allowed? The coder clearly knows that it is 2, so why is he writing that? Many queries are generated by automatic tools that definitely intend what they say.