Re: "How do I ..." SQL question

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От Bob
Тема Re: "How do I ..." SQL question
Дата
Msg-id 41ED5F62.1270.30449FEC@localhost
обсуждение исходный текст
Ответ на Re: "How do I ..." SQL question  (PFC <lists@boutiquenumerique.com>)
Список pgsql-sql
PFC wrote:

>   Return only four rows beginning at second row:
> >
> > SELECT count(*) AS count, name, year FROM a
> >   GROUP BY name, year
> >   ORDER BY count DESC, name ASC
> >   LIMIT 4 OFFSET 1;
> >
> >  count   name   year
> > ------- ------ ------
> >    3     joe    2004 s,e,e
> >    2     bob    2003 w,e
> >    2     kim    2003 s,s
> >    2     sue    2004 s,w
> >
> > Select only places visited included in LIMITed query:
> 
> 
>     Is this :
> 
>     SELECT DISTINCT place FROM a,(
> SELECT count(*) AS count, name, year FROM a
>     GROUP BY name, year
>     ORDER BY count DESC, name ASC
>     LIMIT 4 OFFSET 1
> ) as foo WHERE name=foo.name AND year=foo.year
> 
>     Problem with this approach is that you'll have to run the query twice,  
> one to get the hitlist by user, one for the places...
> 
> >
> > SELECT DISTINCT place FROM a ????;
> >
> >  place
> > -------
> >  south
> >  west
> >  east

Thanks, this worked.  As it happens, I am already creating a temporary table
for the hitlist for other uses so that isn't a problem.

-Bob


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