Re: xpath_string and group by

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От Martijn van Oosterhout
Тема Re: xpath_string and group by
Дата
Msg-id 20060829105458.GB22806@svana.org
обсуждение исходный текст
Ответ на xpath_string and group by  (Perez <arturo@ethicist.net>)
Список pgsql-general
On Sat, Aug 26, 2006 at 03:51:06PM -0400, Perez wrote:
> Hi all,
>
> Using 8.1.4 and contrib/xml2.  When I do a
>
> select xpath_string(note, '//Thing') as note,
>    count(aDate) from theTable
> group by lower(xpath_string(note, '//Thing'))
> order by 2 desc;
>
> I get an error:
> GROUP BY must contain note.
> But I can do that for a plain text/varchar field.  Adding the non-xpath
> note field messes up the grouping.

I wonder if it's getting confused about which "note" you're referring
to in the GROUP BY clause.

> select note, count(aDate) from
>   (select  lower(xpath_string(note, '//Thing')) as note, aDate from
> theTable) as foo
> group by note

This is about the same thing, so why not use that?

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.

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