From: David W Noon <dwnoon@ntlworld.com>
To: pgsql-sql@postgresql.org
Subject: Re: simple (?) join
Date: Sat, 26 Sep 2009 20:53:49 +0100
Message-ID: <20090926205349.5fa284f1@dwnoon.ntlworld.com> (raw)
In-Reply-To: <4ABE6360.20205@emproshunts.com>
References: <200909241616.36933.gary.stainburn@ringways.co.uk>
<20090924194629.44bc236f@dwnoon.ntlworld.com>
<4ABBD34B.9080600@emproshunts.com>
<20090924222106.23a5c1f3@dwnoon.ntlworld.com>
<4ABE6360.20205@emproshunts.com>
On Sat, 26 Sep 2009 14:54:24 -0400, justin wrote about Re: [SQL] simple
(?) join:
[snip]
>Quoting Gary
>"How can I select all from orders and the last (latest) entry from the
>orders_log?"
In that case, a simple Cartesian product will do:
SELECT o.*, maxi.ts
FROM orders AS o,
(SELECT MAX(ol_timestamp) AS ts FROM orders_log) AS maxi;
Since the cardinality of the subquery "maxi" is 1, it will give a result
set with cardinality of the complete orders table.
I don't understand why anybody would want to do that. [De gustibus ... ]
--
Regards,
Dave [RLU #314465]
=======================================================================
david.w.noon@ntlworld.com (David W Noon)
=======================================================================
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: dwnoon@ntlworld.com
Subject: Re: simple (?) join
In-Reply-To: <20090926205349.5fa284f1@dwnoon.ntlworld.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox