From: "Tomasz Myrta" <jasiek@klaster.net>
To: wahab@mimos.my, pgsql-sql@postgresql.org
Subject: Re: How to delete duplicate record
Date: Mon, 10 Feb 2003 08:36:47 +0800
Message-Id: <20030210083647.M23706@klaster.net>
In-Reply-To: <3E4704EA.A7A813CC@mimos.my>
References: <3E4704EA.A7A813CC@mimos.my>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-2

> b2b=> select * from biztypes;
>  bizid |  biztype
> -------+-----------
>  B11   | logistics
>  B11   | logistics
>  B11   | logistics
>  B11   | logistics
>  B11   | logistics
> (5 rows)
> 
> b2b=>delete from biztypes where exists (select * from biztypes b2 where
> biztypes.bizid=b2.bizid)
> 
> DELETE 5
> b2bscm=> select * from test1;
>  bizid | biztype
> -------+---------
> (0 rows)
> 
> all the records been deleted.
> the result should be :
> 
> bizid |  biztype
> -------+-----------
>  B11   | logistics
> 
Sorry, I forgot this code works only if you have any field which is
primary key or any other unique identifier - for example oid.
It will look then:
delete from biztypes where exists (select * from biztypes b2 where
biztypes.bizid=b2.bizid and biztypes.oid<>b2.oid)

If you don't have any unique identifier for rows in your table, the only
way to delete this record is creating a copy of this table:
create table some_copy as
select
 bizid,biztype
from biztypes group by bizid,biztype;
drop table biztypes;
alter table some_copy rename to biztypes;

Regards,
Tomasz Myrta