Re: "left join" not working?

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От Louis-David Mitterrand
Тема Re: "left join" not working?
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Msg-id 20100212115747.GA21659@apartia.fr
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Ответ на Re: "left join" not working?  ("Oliveiros C," <oliveiros.cristina@marktest.pt>)
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On Fri, Feb 12, 2010 at 11:35:02AM -0000, Oliveiros C, wrote:
> My first guess is that
> NULL fails the condition on your WHERE clause,
> p.id_line = 1
> 
> So your WHERE clause introduces an additional level of filtering
> that filters out the NULLs coming from the LEFT JOIN...

So, if I understand correctly, a WHERE filters all results regardless of
join conditions and can turn an OUTER JOIN into an INNER JOIN.

Thanks for pointing that out!


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