Date: Sun, 22 Jun 2003 12:03:35 +0100
From: Paul Thomas <paul@tmsl.demon.co.uk>
To: "pgsql-sql @ postgresql . org" <pgsql-sql@postgresql.org>
Subject: Re: Delete duplicates
Message-ID: <20030622120335.C4067@bacon>
References: <20030622091522.M37248@oasis.net.au>
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	from rudi@oasis.net.au on Sun, Jun 22, 2003 at 10:15:22 +0100
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On 22/06/2003 10:15 Rudi Starcevic wrote:
> 
> 
> Hi,
> 
> I have a table with duplicates and trouble with my SQL.
> I'd like to keep a single record and remove older duplicates.
> For example below of the 6 recods I'd like to keep records
> 4 and 6.
> 
> TABLE: aap
>  id |     keyword
> ----+-----------------
>   1 | LEAGUE PANTHERS
>   2 | LEAGUE PANTHERS
>   3 | LEAGUE PANTHERS
>   4 | LEAGUE PANTHERS
>   5 | LEAGUE BRONCOS
>   6 | LEAGUE BRONCOS
> 
> Here is my SQL so far, it will select records 1 to 5 instead
> of 1,2,3 and 5 only.
> 
> Any help greatly appreciated. I think I need a Group By somewhere in
> there.
> 
> select a1.id
> from aap a1
> where id < ( SELECT max(id) FROM aap AS a2 )
> AND EXISTS
> (
> SELECT *
> FROM aap AS a2
> WHERE a1.keyword = a2.keyword
> )

I just tries this with 7.3.3:

select max(id), keyword from aap where keyword in (select distinct keyword 
from aap) group by keyword;

  max |     keyword
-----------------------
    6 | LEAGUE BRONCOS
    4 | LEAGUE PANTHERS
(2 rows)

HTH

-- 
Paul Thomas
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