From: Paul Thomas <paul@tmsl.demon.co.uk>
To: pgsql-sql @ postgresql . org <pgsql-sql@postgresql.org>
Subject: Re: Delete duplicates
Date: Sun, 22 Jun 2003 12:03:35 +0100
Message-ID: <20030622120335.C4067@bacon> (raw)
In-Reply-To: <20030622091522.M37248@oasis.net.au>
References: <20030622091522.M37248@oasis.net.au>
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
+------------------------------+---------------------------------------------+
| Thomas Micro Systems Limited | Software Solutions for the Smaller
Business |
| Computer Consultants |
http://www.thomas-micro-systems-ltd.co.uk |
+------------------------------+---------------------------------------------+
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To: pgsql-sql@postgresql.org
Cc: paul@tmsl.demon.co.uk
Subject: Re: Delete duplicates
In-Reply-To: <20030622120335.C4067@bacon>
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