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Date: Sat, 26 Sep 2009 16:15:37 -0400
From: justin <justin@emproshunts.com>
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To: David W Noon <dwnoon@ntlworld.com>, pgsql-sql@postgresql.org
Subject: Re: simple (?) join
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David W Noon wrote:
<blockquote cite="mid:20090926205349.5fa284f1@dwnoon.ntlworld.com"
 type="cite">
  <pre wrap="">On Sat, 26 Sep 2009 14:54:24 -0400, justin wrote about Re: [SQL] simple
(?) join:

[snip]
  </pre>
  <blockquote type="cite">
    <pre wrap="">Quoting Gary
"How can I select all from orders and the last (latest) entry from the 
orders_log?"
    </pre>
  </blockquote>
  <pre wrap=""><!---->
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 ... ]
  </pre>
</blockquote>
<br>
Guessing here <br>
<br>
&nbsp;Answer to return the last time someone either viewed or edited the
order.<br>
<br>
This is a very common audit requirement to track who what, when and why
something happened.&nbsp; <br>
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