From: A. Kretschmer <andreas.kretschmer@schollglas.com>
To: pgsql-sql@postgresql.org
Subject: Re: selecting latest record
Date: Tue, 22 Sep 2009 12:08:46 +0200
Message-ID: <20090922100846.GD5415@a-kretschmer.de> (raw)
In-Reply-To: <20090922094457.GA24885@apartia.fr>
References: <20090922094457.GA24885@apartia.fr>
In response to Louis-David Mitterrand :
> Hi,
>
> I have a simple table
>
> price(id_product, price, date)
>
> which records price changes for each id_product. Each time a price
> changes a new tuple is created.
>
> What is the best way to select only the latest price of each id_product?
There are several ways to do that, for instance with DISTINCT ON (only
postgresql):
test=*# select * from price ;
id_product | price | datum
------------+-------+------------
1 | 10 | 2009-09-01
1 | 12 | 2009-09-10
2 | 11 | 2009-09-10
2 | 8 | 2009-09-13
(4 rows)
test=*# select distinct on (id_product) id_product, price from price order by id_product, datum desc;
id_product | price
------------+-------
1 | 12
2 | 8
(2 rows)
Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
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To: pgsql-sql@postgresql.org
Cc: andreas.kretschmer@schollglas.com
Subject: Re: selecting latest record
In-Reply-To: <20090922100846.GD5415@a-kretschmer.de>
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