31) What command adds a primary Key to an existing table 32) Give an example of an Insert command that inserts multiple rows: INSERT INTO ________ as _______________________________________________________ 33) For the commands, below, which tables will be updated ? Update Customers set discnt = discnt * 1.1; Update Products set quantity = quantity * 2; Rollback; Update Orders set qty = qty * 1.5; Update Agents set city = Olympia; Commit; _________________________, _________________________ 34) What is the difference between the three commands below ? ALTER TABLE Employee add FOREIGN KEY did REFERENCES Department; ALTER TABLE Employee add FOREIGN KEY did REFERENCES Department ON DELETE CASCADE; ALTER TABLE Employee add FOREIGN KEY did REFERENCES Department ON DELETE SET NULL; _________________________, _________________________