Received: from maia.hub.org (maia-3.hub.org [200.46.204.243])
	by mail.postgresql.org (Postfix) with ESMTP id AC0F4B5DBFB
	for <pgsql-docs-postgresql.org@mail.postgresql.org>;
	Wed, 12 Oct 2011 17:59:09 -0300 (ADT)
Received: from mail.postgresql.org ([200.46.204.86])
	by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia,
	port 10024) with ESMTP id 57731-01-4 for
	<pgsql-docs-postgresql.org@mail.postgresql.org>;
	Wed, 12 Oct 2011 20:59:03 +0000 (UTC)
X-Greylist: from auto-whitelisted by SQLgrey-1.8.0-rc2
Received: from momjian.us (momjian.us [70.90.9.53])
	by mail.postgresql.org (Postfix) with ESMTP id CBA24B5DBF4
	for <pgsql-docs@postgresql.org>; Wed, 12 Oct 2011 17:59:02 -0300 (ADT)
Received: (from bruce@localhost) by momjian.us (8.11.6/8.11.6) id
 p9CKx4K06548;
	Wed, 12 Oct 2011 16:59:04 -0400 (EDT)
From: Bruce Momjian <bruce@momjian.us>
Message-Id: <201110122059.p9CKx4K06548@momjian.us>
Subject: Re: 5.3.5. Foreign Keys (The SQL Language) possible
 enhance
In-Reply-To: <BANLkTin1u+x6gnHq38W9dkmQyTh+24iqyA@mail.gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Date: Wed, 12 Oct 2011 16:59:04 -0400 (EDT)
CC: Grzegorz Szpetkowski <gszpetkowski@gmail.com>, pgsql-docs@postgresql.org
X-Mailer: ELM [version 2.4ME+ PL124 (25)]
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="ELM1318453144-1529-5_"
Content-Transfer-Encoding: 7bit
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=-2.404 tagged_above=-5 required=5 tests=BAYES_00=-1.9,
	RP_MATCHES_RCVD=-0.504
X-Spam-Level: 
X-Archive-Number: 201110/38
X-Sequence-Number: 7038


--ELM1318453144-1529-5_
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="US-ASCII"

Robert Haas wrote:
> On Fri, May 6, 2011 at 9:50 PM, Grzegorz Szpetkowski
> <gszpetkowski@gmail.com> wrote:
> > I have some remark about
> >
> > "Now it is impossible to create orders with product_no entries that do
> > not appear in the products table."
> >
> > http://www.postgresql.org/docs/9.0/static/ddl-constraints.html#DDL-CONSTRAINTS-FK
> [...]
> >
> > There is still possibility to add product_no (exactly NULL) value,
> > which does not appear (cannot because of primary key nature) in
> > products table. To get "full solution" you need create orders table as
> >
> > CREATE TABLE orders (
> > ? ?order_id integer PRIMARY KEY,
> > ? ?product_no integer REFERENCES products (product_no) NOT NULL,
> > ? ?quantity integer
> > );
> 
> I don't think we should change the example, but we could probably
> clarify the wording.

Done with the attached patch.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

--ELM1318453144-1529-5_
Content-Transfer-Encoding: 7bit
Content-Type: text/x-diff
Content-Disposition: inline; filename="/rtmp/null"

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
new file mode 100644
index c624fc2..ea840fb
*** a/doc/src/sgml/ddl.sgml
--- b/doc/src/sgml/ddl.sgml
*************** CREATE TABLE orders (
*** 688,694 ****
      quantity integer
  );
  </programlisting>
!     Now it is impossible to create orders with
      <structfield>product_no</structfield> entries that do not appear in the
      products table.
     </para>
--- 688,694 ----
      quantity integer
  );
  </programlisting>
!     Now it is impossible to create orders with non-NULL
      <structfield>product_no</structfield> entries that do not appear in the
      products table.
     </para>

--ELM1318453144-1529-5_--