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From: Stefan Becker <pgsql@yukonho.de>
To: pgsql-sql@postgresql.org
Subject: Re: Selecting exactly one row for each column value
Date: Tue, 6 Mar 2007 19:14:49 +0100
Message-ID: <200703061914.50151.pgsql@yukonho.de> (raw)
In-Reply-To: <82hcsy4do7.fsf@mid.bfk.de>
References: <82hcsy4do7.fsf@mid.bfk.de>

Am Dienstag, 6. März 2007 16:03 schrieb Florian Weimer:

>  a | b | c
> ---+---+---
>  5 | 6 | 7
>  2 | 3 | 4
>  1 | 2 | 3

Hi,
couldn't you accomplish this by:

select distinct on (a) * from tablename order by a;


here:

create table tab (a int,b int,c int);
insert into tab values (1,2,3);
insert into tab values (5,6,7);
insert into tab values (1,2,3);
insert into tab values (2,3,4);
insert into tab values (1,2,2);
insert into tab values (2,3,4);

select * from tab;
 a | b | c
---+---+---
 1 | 2 | 3
 5 | 6 | 7
 1 | 2 | 3
 2 | 3 | 4
 1 | 2 | 2
 2 | 3 | 4
(6 rows)

select distinct on (a) * from tab order by a;
 a | b | c
---+---+---
 1 | 2 | 3
 2 | 3 | 4
 5 | 6 | 7
(3 rows)



my regards,


Stefan






-- 
email: stefan@yukonho.de
tel  : +49 (0)6232-497631
http://www.yukonho.de



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