From: Richard Huxton <dev@archonet.com>
To: aarni@kymi.com
Cc: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Subject: Re: Originally created and last_mod by whom and when ?
Date: Wed, 14 Nov 2007 11:28:55 +0000
Message-ID: <473ADBF7.1060908@archonet.com> (raw)
In-Reply-To: <200711141306.34996.aarni@kymi.com>
References: <200711141306.34996.aarni@kymi.com>
Aarni Ruuhimäki wrote:
> Hello,
>
> In a web app (Pg 8.2.4 + php) I have product and other tables with fields like
>
> product_created timestamp without time zone
> product_created_user_id integer
> product_last_mod timestamp without time zone
> product_last_mod_user_id integer
>
> The person who last modified an item can obviously be someone else who
> originally created it.
>
> I can get the names and timestamps with two separate queries but how can I do
> a single query to get the names of both ?
Alias the tables, so you can join to the user-table twice.
SELECT p.*, u_cre.username as created_by, u_mod.username as modified_by
FROM
products p
LEFT JOIN
app_users u_cre ON p.product_created_user_id = u_cre.id
LEFT JOIN
app_users u_mod ON p.product_last_mod_user_id = u.mod.id
;
--
Richard Huxton
Archonet Ltd
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, aarni@kymi.com
Subject: Re: Originally created and last_mod by whom and when ?
In-Reply-To: <473ADBF7.1060908@archonet.com>
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