Re: Optimizing maximum/minimum queries (yet again)

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От Bruno Wolff III
Тема Re: Optimizing maximum/minimum queries (yet again)
Дата
Msg-id 20050409020622.GB3177@wolff.to
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Ответ на Optimizing maximum/minimum queries (yet again)  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Optimizing maximum/minimum queries (yet again)  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Fri, Apr 08, 2005 at 20:50:09 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 
>     SELECT (SELECT x FROM tab WHERE ... ORDER BY x LIMIT 1),
>            (SELECT y FROM tab WHERE ... ORDER BY y DESC LIMIT 1);
> Comments?  Anyone see anything I missed?

Are NULLs a problem? In the second case above, wouldn't you get NULL
instead of the value returned by max if there were some NULL and some
not NULL values?


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