Re: Ambiguous usage of 'any' in explanation
От | Bruce Momjian |
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Тема | Re: Ambiguous usage of 'any' in explanation |
Дата | |
Msg-id | 20181012150433.GA12966@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
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Список | pgsql-docs |
On Fri, Oct 12, 2018 at 01:42:03PM +0300, KES wrote: > - The result is NULL if the comparison does not return true for any row, > + The result is NULL if no comparison with a subquery row returns true, > and it returns NULL for at least one row. > -The result of ANY is “true” if the comparison returns true for any subquery > row. The result is “false” if the comparison returns false for every subquery > row (including the case where the subquery returns no rows). The result is NULL > if the comparison does not return true for any row, and it returns NULL for at > least one row. > > Similary to: > >The result of ALL is "false" even if *at least one* row yield false > > +The result of ANY is "true" if at least one row yields true. > The result of ANY is "false" if all rows yield false > The result of ANY is NULL if no one row yelds true and at least one row yields > NULL > When subquery return no rows the result of ANY is "false" > > sentences are short, easy to spot when and how result is changed 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. 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. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
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