Re: SELECT DISTINCT ON bug?

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От Martijn van Oosterhout
Тема Re: SELECT DISTINCT ON bug?
Дата
Msg-id 20030521084351.GA15143@svana.org
обсуждение исходный текст
Ответ на Re: SELECT DISTINCT ON bug?  (Jean-Christian Imbeault <jc@mega-bucks.co.jp>)
Список pgsql-general
On Wed, May 21, 2003 at 05:08:33PM +0900, Jean-Christian Imbeault wrote:
> Martijn van Oosterhout wrote:
> >
> >Drop the comma after the distinct on.
> >
> >SELECT distinct on(dai_genres.id) dsc from dai_genres,
>
> Ok, that worked. But accroding to "\h select" the syntax is:
>
> SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]
>     * | expression [ AS output_name ] [, ...]
>
>
> I gather that to mean SELECT DISTINCT ON (*) , ...
>
> Is the syntax give by "\h select" wrong or am I misinterpreting it?

You're misinterpreting it, though I must admit it does seem ambiguous. It
should be read as:

SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]
   { * | expression [ AS output_name ] [, ...] }

See the {}.

Hope this helps,

--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> "the West won the world not by the superiority of its ideas or values or
> religion but rather by its superiority in applying organized violence.
> Westerners often forget this fact, non-Westerners never do."
>   - Samuel P. Huntington

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