postgresql7.1 select count(distinct h.community_key) from dotlrn_communities h, dotlrn_clubs c where h.parent_community_id is not null or c.club_id = h.community_id select count(distinct dotlrn_communities_full.community_id) from dotlrn_classes, dotlrn_communities_full where dotlrn_communities_full.community_type = dotlrn_classes.class_key