Re: DELETE FROM t WHERE EXISTS

From: "Tomasz Myrta" <jasiek(at)klaster(dot)net>
To: "Dan Langille" <dan(at)langille(dot)org>, pgsql-sql(at)postgresql(dot)org
Subject: Re: DELETE FROM t WHERE EXISTS
Date: 2003-02-28 13:28:27
Message-ID: 20030228212827.M96860@klaster.net
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> Hi folks,
>
> I wanted to delete "old" rows from a table. These are the rows I
> want to keep:
>
> SELECT *
> FROM clp
> ORDER BY commit_date
> LIMIT 100
>
> So I tried this:
>
> DELETE FROM clp
> WHERE NOT EXISTS (
> SELECT *
> FROM clp
> ORDER BY commit_date
> LIMIT 100);
>
> Uhh uhh, nothing deleted. I don't understand why.
>
> OK, I can do this instead:
>
> DELETE from clp
> where commit_log_id NOT in (
> SELECT commit_log_id
> FROM clp
> ORDER BY commit_date
> LIMIT 100);
>
> Can you think of a better way?
delete from clp where commit_date < (select commit_date from clp order by
commit_date limit 1 offset 100);
Regards,
Tomasz Myrta

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