From: Jean-Luc Lachance <jllachan@sympatico.ca>
To: Achilleus Mantzios <achill@matrix.gatewaynet.com>
Cc: Christoph Haller <ch@rodos.fzk.de>
Cc: pgsql-sql@postgresql.org
Subject: Re: How to delete the not DISTINCT ON entries
Date: Wed, 16 Jun 2004 10:14:14 -0400
Message-ID: <40D055B6.5020301@sympatico.ca> (raw)
In-Reply-To: <Pine.LNX.4.44.0406161511460.2590-100000@matrix.gatewaynet.com>
References: <Pine.LNX.4.44.0406161511460.2590-100000@matrix.gatewaynet.com>
If you do not have foreign key restrinctions, create a temp table from
the select as:
CREATE TEMP TABLE tmp AS SELECT DISTINCT ON (location) location, time,
report FROM weatherReports ORDER BY location, time DESC;
TRUNCATE weatherReports; INSERT INTO weatherReports SELECT * FROM tmp;
HTH
Achilleus Mantzios wrote:
> O kyrios Christoph Haller egrapse stis Jun 16, 2004 :
>
>
>>Referring to the DISTINCT ON example
>>
>>SELECT DISTINCT ON (location) location, time, report
>>FROM weatherReports
>>ORDER BY location, time DESC;
>
>
> maybe smth like
>
> delete from weatherReports where (location,time,report) not in
> (SELECT DISTINCT ON (location) location, time, report FROM weatherReports
> ORDER BY location, time DESC)
>
> Note:
> Order by is very important, since it affects which rows are deleted.
>
>
>>How would I delete those entries skipped by the DISTINCT ON expression?
>>
>>TIA
>>
>>Regards, Christoph
>>
>>
>>
>>---------------------------(end of broadcast)---------------------------
>>TIP 6: Have you searched our list archives?
>>
>> http://archives.postgresql.org
>>
>
>
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To: pgsql-sql@postgresql.org
Cc: jllachan@sympatico.ca, achill@matrix.gatewaynet.com, ch@rodos.fzk.de
Subject: Re: How to delete the not DISTINCT ON entries
In-Reply-To: <40D055B6.5020301@sympatico.ca>
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