SELECT COUNT(DISTINCT)

Hello!

   I am trying to execute query:
SELECT city_id, COUNT(DISTINCT pos_id)
   ...
GROUP BY city_id ;

   but got the error:
ERROR:  parser: parse error at or near "distinct"

   It is me who do not understand SQL or postgres does not implement it?

Oleg.
---- 
    Oleg Broytmann     http://members.xoom.com/phd2/     phd2@earthling.net
           Programmers don't die, they just GOSUB without RETURN.