Date: Thu, 24 May 2007 21:42:42 +0200
From: "A. Kretschmer" <andreas.kretschmer@schollglas.com>
To: pgsql-sql@postgresql.org
Subject: Re: group by day
Message-ID: <20070524194242.GA21054@a-kretschmer.de>
References: <04c201c79e34$4e3877c0$143c520a@ntc2s.comsquared.com>
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am  Thu, dem 24.05.2007, um 14:49:47 -0400 mailte Edward W. Rouse folgendes:
> I have an audit table that I am trying to get a count of the number of distinct
> entries per day by the external table key field. I can do a
>  
> select count(distinct(id)) from audit where timestamp >= '01-may-2007'
>  
> and get a total count. What I need is a way to group on each day and get a
> count per day such that the result would be something like
>  
> date                    count
> 01-may-2007        107
> 02-may-2007        215
> 03-may-2007        96
> 04-may-2007        0
>  
>  
> I would prefer the 0 entries be included but can live without them. Thanks.

You are searching for GROUP BY.

A simple example:

test=*# select * from foo;
         ts          | val
---------------------+-----
 2007-05-01 08:00:00 |  10
 2007-05-01 08:00:00 |  20
 2007-05-02 10:00:00 |  20
 2007-05-02 11:00:00 |  30
(4 rows)

Time: 1.079 ms
test=*# select ts::date, sum(val) from foo group by 1;
     ts     | sum
------------+-----
 2007-05-02 |  50
 2007-05-01 |  30
(2 rows)


Andreas
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Andreas Kretschmer
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