MariaDB TRANSACTION

MariaDB TRANSACTION

• Transaction—A block of SQL statements

• Rollback—The process of undoing specified SQL statements

• Commit—Writing unsaved SQL statements to the database tables

• Savepoint—A temporary placeholder in a transaction set to which you can issue a rollback (as opposed to rolling back an entire transaction) 

始终以START TRANSACTION为新起点遇到最后的ROLLBACK savepoint或COMMIT时自动关闭

ROLLBACK

(jlive)[crashcourse]>SELECT * FROM ordertotals; START TRANSACTION;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

|     20009 |   40.78 |

|     20009 |   40.78 |

+-----------+---------+

6 rows in set (0.00 sec)

(jlive)[crashcourse]>START TRANSACTION;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>DELETE FROM ordertotals;

Query OK, 6 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

Empty set (0.00 sec)

(jlive)[crashcourse]>ROLLBACK;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

|     20009 |   40.78 |

|     20009 |   40.78 |

+-----------+---------+

6 rows in set (0.00 sec)

COMMIT

START TRANSACTION;
DELETE FROM orderitems WHERE order_num = 20010; 

DELETE FROM orders WHERE order_num = 20010; 

COMMIT; 

SAVEPOINT

(jlive)[crashcourse]>START TRANSACTION;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

|     20009 |   40.78 |

|     20009 |   40.78 |

+-----------+---------+

6 rows in set (0.00 sec)

(jlive)[crashcourse]>SAVEPOINT delete1;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>DELETE FROM ordertotals WHERE order_num = 20009;

Query OK, 2 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

+-----------+---------+

4 rows in set (0.01 sec)

(jlive)[crashcourse]>SAVEPOINT delete2;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>DELETE FROM ordertotals WHERE order_num = 20005;

Query OK, 1 row affected (0.01 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

+-----------+---------+

3 rows in set (0.00 sec)

(jlive)[crashcourse]>SAVEPOINT delete3;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>DELETE FROM ordertotals WHERE order_num = 20008;

Query OK, 1 row affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20006 |   58.30 |

|     20007 | 1060.00 |

+-----------+---------+

2 rows in set (0.00 sec)

(jlive)[crashcourse]>ROLLBACK TO delete3;

Query OK, 0 rows affected (0.01 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

+-----------+---------+

3 rows in set (0.00 sec)

(jlive)[crashcourse]>ROLLBACK TO delete2;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

+-----------+---------+

4 rows in set (0.00 sec)

(jlive)[crashcourse]>ROLLBACK TO delete1;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM ordertotals;

+-----------+---------+

| order_num | total   |

+-----------+---------+

|     20005 |  158.86 |

|     20006 |   58.30 |

|     20007 | 1060.00 |

|     20008 |  132.50 |

|     20009 |   40.78 |

|     20009 |   40.78 |

+-----------+---------+

 

6 rows in set (0.00 sec)

修改默认的COMMIT方式

(jlive)[crashcourse]>SHOW VARIABLES LIKE 'autocommit';

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| autocommit    | ON    |

+---------------+-------+

1 row in set (0.00 sec)

(jlive)[crashcourse]>SET autocommit = 0;

Query OK, 0 rows affected (0.00 sec)

(jlive)[crashcourse]>SHOW VARIABLES LIKE 'autocommit';

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| autocommit    | OFF   |

+---------------+-------+

 

1 row in set (0.00 sec)