Re: [HACKERS] subselect

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От Bruce Momjian
Тема Re: [HACKERS] subselect
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Msg-id 199801060506.AAA11991@candle.pha.pa.us
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Ответ на Re: [HACKERS] subselect  ("Thomas G. Lockhart" <lockhart@alumni.caltech.edu>)
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>
> > BTW, note that for _expression_ subqueries (which are introduced without
> > IN, EXISTS, ALL, ANY - this follows Sybase' naming) - as in your examples -
> > we have to check that subquery returns single tuple...
>
> It might be nice to have a tuple-counting operation or query node (is this the right
> terminology?) which could be used to help implement EXISTS. It might help to
> re-implement the count(*) function also.

In the new code, count(*) picks a column from one of the tables to count
on.


--
Bruce Momjian
maillist@candle.pha.pa.us

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