Here is the start of a query for pulling out travel requirements for conference attendees. SELECT P.last_name, P.first_name, CPT.arrival_from, CPT.arrival_to, CPT.need_accommodation FROM conference_person_travel CPT, conference_person CP, conference C, person P WHERE CPT.need_accommodation AND CPT.conference_person_id = CP.conference_person_id AND P.person_id = CP.person_id AND CP.conference_id = C.conference_id AND C.acronym = ‘BSDCan2012’

After a very long effort, this is the solution: CREATE OR REPLACE FUNCTION conflict.conflict_statistics(conference_id integer, OUT conflict_level text, OUT conflicts integer) RETURNS SETOF record LANGUAGE plpgsql AS $function$ #variable_conflict use_variable DECLARE conflict TEXT; conflict_rows INTEGER; BEGIN FOR conflict_level IN SELECT conflict_level.conflict_level FROM conflict.conflict_level WHERE conflict_level.conflict_level ‘silent’ ORDER BY rank LOOP conflicts = 0; FOR conflict IN SELECT conference_phase_conflict.conflict FROM conflict.conference_phase_conflict INNER JOIN conference ON ( conference.conference_id = conference_id AND conference.conference_phase = conference_phase_conflict.conference_phase )