From: | "Vadim B(dot) Mikheev" <vadim(at)sable(dot)krasnoyarsk(dot)su> |
---|---|
To: | "Thomas G(dot) Lockhart" <lockhart(at)alumni(dot)caltech(dot)edu> |
Cc: | hackers(at)postgresql(dot)org |
Subject: | Re: [HACKERS] what standard say ... |
Date: | 1998-02-06 07:48:58 |
Message-ID: | 34DAC06A.C8E9729@sable.krasnoyarsk.su |
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Lists: | pgsql-hackers |
Thomas G. Lockhart wrote:
>
> > vac=> select count(*) from test where exists (select t1.y from test t1 where t1.y = x);
> > ^
> > Is this correlated subquery or not ?
> > (Note, that I don't use x with t1. prefix here)
> > With current parser this works as un-correlated subquery...
>
> >From "The SQL Standard", 3rd ed., Date and Darwen:
>
> "... each unqualified column name is _implicitly_ qualified by a range variable name
> defined (explicitly or implicitly) in the nearest applicable FROM clause." (the emphasis
> is from the book, not me)
>
> It goes on to recommend reading the standard for full understanding, but it is pretty
> clear that your interpretation is correct; in the example above x is implicitly equivalent
> to t1.x.
Ok. Nice to know that we are correct here :)
Vadim
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