Assuming that pessimistic locking is being used but the two-phase locking protocol is not, create a chronological list of the locking unlocking and data manipulation activities that would occur during the complete processing of the transaction described in Problem 6a. What if two-phase locking is used? The transaction in 6a is:

BEGIN TRANSACTION

INSERT INTO INVOICE

VALUES(10983, '10010', '11-MAY-2014', 118.80, '30', 'OPEN);

INSERT INTO LINE VALUES(10983, 1, '11QER/31', 1, 110.00);

UPDATE PRODUCT

SET PQTYOH=PQTYOH-1 WHERE P_CODE=11QER/31;

UPDATE CUSTOMER

SET CUS_DATELSTPUR='11-MAY-2014',

CUS_BALANCE=CUS_BALANCE+118.80

WHERE CUS_CODE='10010';

COMMIT;