From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | KES <kes-kes(at)yandex(dot)ru> |
Cc: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, "pgsql-docs(at)lists(dot)postgresql(dot)org" <pgsql-docs(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Ambiguous usage of 'any' in explanation |
Date: | 2018-10-13 17:31:48 |
Message-ID: | 20181013173148.GA25417@momjian.us |
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Lists: | pgsql-docs |
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(dot)g(dot)johnston(at)gmail(dot)com>:
>
> On Fri, Oct 12, 2018 at 8:04 AM Bruce Momjian <bruce(at)momjian(dot)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(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
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