ТЕМА:

SELECT st.name AS магазин,to_char(sals.date_when_sold, 'MM-YY') AS месяц,substr(to_char(sals.date_when_sold, 'MM-YY'),4,2), SUM(sals.kolvo * gds.price) AS выручка
FROM stores st
JOIN departmentsstores dps ON (dps.id_store = st.id_store)
JOIN goodsinstores gds ON (gds.id_department = dps.id_department)
JOIN goods g ON (g.id_good = gds.id_good)
JOIN sales sals ON (sals.id_good = g.id_good)
GROUP BY grouping sets((st.name, to_char(sals.date_when_sold, 'MM-YY')),substr(to_char(sals.date_when_sold, 'MM-YY'),4,2))
ORDER BY to_char(sals.date_when_sold, 'MM-YY'), st.name;