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Date: Fri, 02 Feb 2007 14:54:24 +0100
From: =?ISO-8859-1?Q?Mezei_Zolt=E1n?= <mezei.zoltan@telefor.hu>
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To: Ezequias Rodrigues da Rocha <ezequias.rocha@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Duplicate records
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Ezequias Rodrigues da Rocha wrote:
> Hi list,
>
> I am making some data minning and would like to know if someone tell 
> me how to retrieve the duplicate records based in one or two fields of 
> my table.
>
> Any help would be welcomed.
You can use a simple query like this one:

select t1.id, t2.id
from table t1, table t2
where t1.record1 = t2.record1
      and t1.record2 = t2.record2
      and t1.id != t2.id

This one lists the ids of the matching records. You may need to fine 
tune it to your needs, e.g. use distinct or replace the != with <.

Zizi