BEGIN;
SELECT sum(salary) OVER w, avg(salary) OVER w
  FROM empsalary
  WINDOW w AS (PARTITION BY depname ORDER BY salary DESC);
END;

CREATE FUNCTION days_of_week() RETURNS SETOF text AS $$
BEGIN
  FOR i IN 7 .. 13 LOOP
    RETURN NEXT to_char(to_date(i::text,'J'),'TMDy');
  END LOOP;
END;
$$ STABLE LANGUAGE plpgsql;