Re: Ambiguous usage of 'any' in explanation

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От Bruce Momjian
Тема Re: Ambiguous usage of 'any' in explanation
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Msg-id 20181013173148.GA25417@momjian.us
обсуждение исходный текст
Ответ на Ambiguous usage of 'any' in explanation  (PG Doc comments form <noreply@postgresql.org>)
Ответы Re: Ambiguous usage of 'any' in explanation  ("David G. Johnston" <david.g.johnston@gmail.com>)
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On Sat, Oct 13, 2018 at 12:25:38PM +0300, KES wrote:
> >or NULL if any of the comparisons result in unknown
> result in unknown??

Well, SQL has a three-valued logic, and UNKOWN values are treated like
NULL.  For me they have always been the same, and I would like to avoid
"unknown" in this context, if possible.

---------------------------------------------------------------------------

> 13.10.2018, 00:37, "David G. Johnston" <david.g.johnston@gmail.com>:
> 
>     On Fri, Oct 12, 2018 at 8:04 AM Bruce Momjian <bruce@momjian.us> wrote:
> 
>         Sorry, but I don't like this wording.  The problem is that the
>         comparison has two row sets --- the left-hand side, and the right-hand
>         side.
> 
> 
>     Huh...the left hand side must be a non-set scalar or row constructor.
> 
> 
>           Each row on the left-hand side is compared with the row set on
>         the right.  I also don't like people thinking about the result of ANY
>         since it is really <comparison> ANY that is being used.
> 
> 
>     Then there is some more rewording to be done since: "The result of ANY is
>     “true” if any true result is obtained." (v10; 9.22.4)
> 
>     Maybe:
> 
>     The result of ANY is “true” if the comparison returns true for any subquery
>     row; otherwise the result is “false” (or NULL if any of the comparisons
>     result in unknown)
> 
>     David J.
> 
> 

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
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