Re: DISTINCT ON ... without distinct null values ?

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От Fduch the Pravking
Тема Re: DISTINCT ON ... without distinct null values ?
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Msg-id 20020419033040.A1388@zombie.antar.bryansk.ru
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Ответ на DISTINCT ON ... without distinct null values ?  ("Albrecht Berger" <berger1517@gmx.ch>)
Список pgsql-sql
On Thu, Apr 18, 2002 at 04:43:25PM +0200, Albrecht Berger wrote:
> Hello,
> I've got a table which I query with something like " SELECT DISTINCT ON("c")
> FROM table ... " .
> 
> Not every row in the column "c" does have a value, some are null.
> My problem is, that I want to eliminate double values in "c" only if they
> are not null !

CREATE SEQUENCE tmp_seq;
SELECT DISTINCT ON (COALESCE("c", nextval('tmp_seq')) * FROM table ...
DROP SEQUENNCE tmp_seq;

or even

SELECT DISTINCT ON (COALESCE("c", random())) * FROM table ...

Not sure I'm right...

-- 
Fduch M. Pravking


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