Re: self join

From: Jasen Betts <jasen(at)xnet(dot)co(dot)nz>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: self join
Date: 2011-05-15 02:36:46
Message-ID: iqne7u$ssa$2@reversiblemaps.ath.cx
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On 2011-05-14, Seb <spluque(at)gmail(dot)com> wrote:
> Hi,
>
> This probably reflects my confusion with how self joins work.
>
> Suppose we have this table:

> If I want to get a table with records where none of the values in column
> b are found in column a, I thought this should do it:

use the "NOT IN" operator with a subquery to retch the disallowed
values.

select * from tmp where a NOT IN (select b from tmp);

--
⚂⚃ 100% natural

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