select m.cust, m.odate, m.ono, d.dno, i.descr, i.units, d.qty, d.tot_price from master_order m JOIN detail_order d USING (ono) JOIN inventory i USING (ino);
	
update master_order set ono=999 where ono=1;
-- ERROR:  update or delete on "master_order" violates foreign key constraint "detail_order_ono_fkey" on "detail_order"
-- DETAIL:  Key (ono)=(1) is still referenced from table "detail_order".
update inventory set ino=999 where ino=1;
-- ERROR:  update or delete on "inventory" violates foreign key constraint "detail_order_ino_fkey" on "detail_order"
-- DETAIL:  Key (ino)=(1) is still referenced from table "detail_order".
update detail_order set dno=999 where dno=1;