Re: Outer joins and equivalence

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От Simon Riggs
Тема Re: Outer joins and equivalence
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Msg-id 1211981950.4489.473.camel@ebony.site
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Ответ на Re: Outer joins and equivalence  (Matthew Wakeling <matthew@flymine.org>)
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On Wed, 2008-05-28 at 11:45 +0100, Matthew Wakeling wrote:
> On Tue, 27 May 2008, Simon Riggs wrote:
> > I do recognise that we would *not* be able to deduce this form of SQL
> >
> > A JOIN B ON (a.id = c.id) LEFT JOIN C ON (b.id = c.id)
>
> Surely that would not be valid SQL?

You are right, but my point was about inferences during SQL planning,
not about initial analysis of the statement.

--
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support


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