Re: simple (?) join

From: David W Noon <dwnoon(at)ntlworld(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: simple (?) join
Date: 2009-09-24 18:46:29
Message-ID: 20090924194629.44bc236f@dwnoon.ntlworld.com
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On Thu, 24 Sep 2009 16:16:36 +0100, Gary Stainburn wrote about [SQL]
simple (?) join:

>create table orders (
>o_id serial primary key
>...
>);
>
>create table orders_log (
>ol_id serial primary key,
>o_id int4 not null references orders(o_id),
>ol_timestamp timestamp,
>ol_user,
>);
>
>How can I select all from orders and the last (latest) entry from the
>orders_log?

SELECT * FROM orders
WHERE o_id IN (SELECT o_id FROM orders_log
WHERE ol_timestamp = (SELECT MAX(ol_timestamp) FROM orders_log));

No joins required.
--
Regards,

Dave [RLU #314465]
=======================================================================
david(dot)w(dot)noon(at)ntlworld(dot)com (David W Noon)
=======================================================================

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