Re: Ambiguous columns

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От Bruno Wolff III
Тема Re: Ambiguous columns
Дата
Msg-id 20050704061245.GA26547@wolff.to
обсуждение исходный текст
Ответ на Ambiguous columns  (Steve Tucknott <steve@retsol.co.uk>)
Список pgsql-novice
On Sun, Jul 03, 2005 at 08:17:01 +0100,
  Steve Tucknott <steve@retsol.co.uk> wrote:
> If I have two tables(taba, tabb) with the same column (column1) name and
> try to do:
>
> SELECT taba.column1 AS column1,tabb.column2 AS column2
>     FROM taba AS a
>          JOIN tabb AS b
>          ON  taba.indexCol = tabb.indexCol
> GROUP BY column1
>
> It tells me that column1 is ambiguous. Is that to be expected? I can
> semi see why - but I thought you could only only group on selected
> fields, and the only 'selected' column1 is that from taba. Minor issue,
> with easy work around.

You have things backwards. You can only select fields that are used in
the group by list or that are aggregates. You can have things used
for grouping that are not output in the select list.

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