Received: from golem.jpl.nasa.gov (IDENT:root@hectic-1.jpl.nasa.gov
	[128.149.68.203]) by hub.org (8.9.2/8.9.1) with ESMTP id IAA22126
	for <pgsql-interfaces@postgreSQL.org>;
	Thu, 4 Mar 1999 08:54:49 -0500 (EST)
	(envelope-from lockhart@alumni.caltech.edu)
Received: from alumni.caltech.edu (localhost [127.0.0.1])
	by golem.jpl.nasa.gov (8.8.5/8.8.5) with ESMTP id NAA06931;
	Thu, 4 Mar 1999 13:54:09 GMT
Sender: tgl@mythos.jpl.nasa.gov
Message-ID: <36DE9081.529561FC@alumni.caltech.edu>
Date: Thu, 04 Mar 1999 13:54:09 +0000
From: "Thomas G. Lockhart" <lockhart@alumni.caltech.edu>
Organization: Caltech/JPL
X-Mailer: Mozilla 4.07 [en] (X11; I; Linux 2.0.36 i686)
MIME-Version: 1.0
To: Valerio Santinelli <tanis@mediacom.it>
CC: "jose' soares" <sferac@bo.nettuno.it>,
	"'pgsql-interfaces@postgreSQL.org'" <pgsql-interfaces@postgreSQL.org>,
	Michael Davis <michael.davis@prevuenet.com>
Subject: Re: [INTERFACES] Foreign Keys
References: <93C04F1F5173D211A27900105AA8FCFC145219@lambic.prevuenet.com>
	<36DC61D6.6DF4E87D@insightdist.com> <36DD1FD2.11561615@mediacom.it>
	<36DD3669.3A62A57F@bo.nettuno.it> <36DD6CEC.967BBD0C@bo.nettuno.it>
	<36DE7632.F0CFF0AC@mediacom.it>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

> Thanks. That was what i was looking for. It's been real useful!
> I also put this other line to handle the inverse case (NULL = field)
> 
>  | NULL_P '=' a_expr
>     { $$ = makeA_Expr(ISNULL, NULL, $3, NULL); }

This leads to a shift/reduce conflict in yacc. I've been working on this
a bit, and have modified gram.y (so far just in my local copy) to allow
Jose's syntax and to allow the same syntax in a constraint declaration.
But this variant may be tougher to do correctly...

                        - Tom