Re: extend "group by" to include "empty relations" ?

peter pilsl wrote:

> But there is a problem now: There are also entries in fn_kat which dont
> have corresponding entries in fn_dokumente and this entries should be
> listed too. With the proper count=0 !!

Your problem is not on the GROUP BY, but rather that you need an outer
join.  Try something like

 select k.kategorie,count(d.oid) from fn_kat k left join fn_dokumente d
 on k.id=d.kategorie group by k.kategorie;

--
Alvaro Herrera                               http://www.PlanetPostgreSQL.org/
"The first of April is the day we remember what we are
the other 364 days of the year"  (Mark Twain)