1. Latihan Lock

2. Transaksi
- BEGIN transaksi COMMIT;
- ROLLBACK; (utk membatalkan)

3. Transaksi
buatlah tabel rekening dan isikan datanya
CREATE TABLE rekening (norek char(10) PRIMARY KEY, nama varchar(30), saldo numeric(10.2));
DESCRIBE mhs;
INSERT INTO rekening VALUES (‘111’,’Bapak’, );
INSERT INTO rekening VALUES (‘222’,’anak’, );
SELECT * FROM rekening;
buatlah transaksi transfer uang 1 juta dari Bapak ke anak

4. Transaksi Jawaban: BEGIN;
UPDATE rekening SET saldo=saldo WHERE nama=‘Bapak’;UPDATE rekening SET saldo=saldo WHERE nama=‘anak’; COMMIT;
Latihan:
UPDATE rekening SET saldo=saldo WHERE nama=‘Bapak’;
ROLLBACK;

5. A
mysql> CREATE TABLE t (i INT) ENGINE = InnoDB; Query OK, 0 rows affected (1.07 sec)
mysql> INSERT INTO t (i) VALUES(1); Query OK, 1 row affected (0.09 sec)
mysql> START TRANSACTION; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT * FROM t WHERE i = 1 LOCK IN SHARE MODE; 1 row in set (0.10 sec)

6. B mysql> START TRANSACTION; Query OK, 0 rows affected (0.00 sec)
mysql> DELETE FROM t WHERE i = 1;

7. A
mysql> DELETE FROM t WHERE i = 1; ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction
Sama-sama minta exclusive lock jadi deadlock

8. Consistent Read

9. A mysql> BEGIN; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT MAX(i) FROM t;
mysql> INSERT INTO t(i) VALUES (4); Query OK, 1 row affected (0.00 sec)

10. B mysql> BEGIN; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT MAX(i) FROM t;
mysql> INSERT INTO t(i) VALUES(4); Query OK, 1 row affected (0.00 sec)
mysql> COMMIT; Query OK, 0 rows affected (0.00 sec)

11. A mysql> COMMIT; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT * FROM t;

12. A
mysql> DELETE FROM t WHERE i=4; Query OK, 2 rows affected (0.00 sec)
mysql> SELECT * FROM t;

13. A mysql> SELECT * FROM t;
mysql> BEGIN; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT MAX(i) FROM t FOR UPDATE;
mysql> INSERT INTO t(i) VALUES (4); Query OK, 1 row affected (0.00 sec)

14. B mysql> SELECT MAX(i) FROM t FOR UPDATE;
mysql> COMMIT; Query OK, 0 rows affected (0.00 sec)

15. B mysql> SELECT MAX(i) FROM t FOR UPDATE;
mysql> INSERT INTO t(i) VALUES(5); Query OK, 1 row affected (0.00 sec)
mysql> COMMIT; Query OK, 0 rows affected (0.01 sec)
mysql> SELECT * FROM t;

16. READ LOCK A mysql> BEGIN; Query OK, 0 rows affected (0.00 sec)
mysql> SELECT MAX(i) FROM t LOCK IN SHARE MODE;

17. B
mysql> UPDATE t SET i = 55 WHERE i=5;

18. A
mysql> COMMIT; Query OK, 0 rows affected (0.00 sec)

19. B
mysql> UPDATE t SET i = 55 WHERE i=5; Query OK, 0 rows affected (6.95 sec) Rows matched: 0 Changed: 0 Warnings: 0
mysql> UPDATE t SET i = 55 WHERE i=5; Query OK, 1 row affected (43.30 sec) Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT * FROM t;