postgresql7.3 select dotlrn_communities_all.community_id from dotlrn_communities_all, dotlrn_member_rels_approved where dotlrn_communities_all.community_id = dotlrn_member_rels_approved.community_id and dotlrn_member_rels_approved.user_id = :user_id order by random () limit 1 select dotlrn_member_rels_approved.user_id from registered_users, acs_rels a, dotlrn_member_rels_approved where dotlrn_member_rels_approved.community_id = :random_comm_id and a.rel_type = 'user_portrait_rel' and a.object_id_one = registered_users.user_id and dotlrn_member_rels_approved.user_id = registered_users.user_id order by random () limit 1