count distinct and group by

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От	Szymon Guz
Тема	count distinct and group by
Дата	7 мая 2015 г. 13:24:09
Msg-id	CAFjNrYtrTMFmRVrz=PyWkm-SBQQq28DvTzmsaYuVP-bqjPERDQ@mail.gmail.com обсуждение исходный текст
Ответы	Re: count distinct and group by Re: count distinct and group by Re: count distinct and group by
Список	pgsql-general

Hi,

I'm not sure why there is a reason for such behaviour.

For this table:

create table bg(id serial primary key, t text);

This works:

select count(id) from bg;

This works:

select count(distinct id) from bg;

And this doesn't:

select count(distinct id) from bg order by id;

ERROR: column "bg.id" must appear in the GROUP BY clause or be used in an aggregate function

LINE 1: select count(distinct id) from bg order by id;

thanks,

Szymon

В списке pgsql-general по дате отправления:

От: Tim Clarke
Дата: 07 мая 2015 г., 11:36:53
Сообщение: Re: detached query?

От: Magnus Hagander
Дата: 07 мая 2015 г., 13:39:07
Сообщение: Re: count distinct and group by