控制事务

SELECT * FROM PRODUCTS_TMP;
+---------+-------------------------+-------+
| PROD_ID | PROD_DESC               | COST  |
+---------+-------------------------+-------+
| 11235   | WITCH COSTUME           | 29.99 |
| 119     | ASSORTED MASKS          |  4.95 |
| 13      | FALSE PARAFFIN TEETH    |  1.10 |
| 15      | ASSORTED COSTUMES       | 10.00 |
| 222     | PLASTIC PUMPKIN 18 INCH |  7.75 |
| 6       | PUMPKIN CANDY           |  1.45 |
| 87      | PLASTIC SPIDERS         |  1.05 |
| 9       | CANDY CORN              |  1.35 |
| 90      | LIGHTED LANTERNS        | 14.50 |
+---------+-------------------------+-------+

START TRANSACTION;

DELETE FROM PRODUCTS_TMP WHERE COST < 14;

COMMIT;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
+---------+------------------+-------+

START TRANSACTION;

UPDATE PRODUCTS_TMP
SET COST = 39.99
WHERE PROD_ID = ‘11235‘;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 39.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
+---------+------------------+-------+

ROLLBACK;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
+---------+------------------+-------+

START TRANSACTION;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

SAVEPOINT sp1;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘11235‘;

SAVEPOINT sp2;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘90‘;

SAVEPOINT sp3;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘2345‘;

SELECT * FROM PRODUCTS_TMP;
Empty set (0.00 sec)

ROLLBACK TO sp2;
SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

-- 回滚到SAVEPOINT sp2后，sp3失效(=RELEASE SAVEPOINT sp3;)
ROLLBACK TO sp3;
ERROR 1305 (42000): SAVEPOINT sp3 does not exist

-- ROLLBACK回滚到上一个COMMIT或ROLLBACK语句（）。
-- 由于之前没有执行过COMMIT，所以这时执行ROLLBACK会撤销全部删除命令
ROLLBACK;
SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

COMMIT;


START TRANSACTION;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

SAVEPOINT sp1;
DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘11235‘;
SAVEPOINT sp2;
DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘90‘;
SAVEPOINT sp3;
DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘2345‘;

ROLLBACK TO sp3;
SELECT * FROM PRODUCTS_TMP;
+---------+---------------+-------+
| PROD_ID | PROD_DESC     | COST  |
+---------+---------------+-------+
| 2345    | OAK BOOKSHELF | 59.99 |
+---------+---------------+-------+

ROLLBACK;
SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

COMMIT;

START TRANSACTION;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

SAVEPOINT sp1;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘11235‘;

SAVEPOINT sp2;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘90‘;

SAVEPOINT sp3;

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘2345‘;

ROLLBACK WORK TO SAVEPOINT sp3;

SELECT * FROM PRODUCTS_TMP;
+---------+---------------+-------+
| PROD_ID | PROD_DESC     | COST  |
+---------+---------------+-------+
| 2345    | OAK BOOKSHELF | 59.99 |
+---------+---------------+-------+

ROLLBACK WORK TO SAVEPOINT sp2;

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+

DELETE FROM PRODUCTS_TMP WHERE PROD_ID = ‘2345‘;
-- 回滚到指定SAVEPOINT之后，该SAVEPOINT失效(= RELEASE SAVEPOINT sp3;)
ROLLBACK TO sp3;
ERROR 1305 (42000): SAVEPOINT sp3 does not exist

SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 90      | LIGHTED LANTERNS | 14.50 |
+---------+------------------+-------+

-- 回滚到第一个SAVEPOINT，恢复包括sp1/sp2/sp3在内的所有数据
ROLLBACK TO sp1;
SELECT * FROM PRODUCTS_TMP;
+---------+------------------+-------+
| PROD_ID | PROD_DESC        | COST  |
+---------+------------------+-------+
| 11235   | WITCH COSTUME    | 29.99 |
| 90      | LIGHTED LANTERNS | 14.50 |
| 2345    | OAK BOOKSHELF    | 59.99 |
+---------+------------------+-------+