Re: Postgres 7.3.5 and count('x')

Поиск
Список
Период
Сортировка
От Peter Eisentraut
Тема Re: Postgres 7.3.5 and count('x')
Дата
Msg-id 200312061746.37190.peter_e@gmx.net
обсуждение исходный текст
Ответ на Re: Postgres 7.3.5 and count('x')  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Postgres 7.3.5 and count('x')  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Postgres 7.3.5 and count('x')  ("Edwin S. Ramirez" <ramirez@idconcepts.org>)
Список pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > What is COUNT('x') supposed to return?  1?  Is that legal SQL?
>
> Why not?

Because there is nothing to count.

In general,

SELECT count(expr) FROM table1;

counts the number of rows in table1 where expr evaluates to not null.  
If table1 is not specified, that rule no longer holds.  At best you 
could assume that table1 is empty and return 0.  But a result of 1 I 
cannot see justified.



В списке pgsql-hackers по дате отправления:

Предыдущее
От: Gaetano Mendola
Дата:
Сообщение: Double linked list with one pointer
Следующее
От: Bruce Momjian
Дата:
Сообщение: Re: 7.4.1 ... slight change of scheduale ...