MySQL事务的SavePoint简介及操作

SAVEPOINT 保存点的名称;

ROLLBACK [WORK] TO 保存点的名称

RELEASE SAVEPOINT 保存点名称;

开启事务: begin
....DML语句....
设置保存点: savepoint 保存点名字
....DML语句....
设置保存点: savepoint 保存点名字2
....DML语句....
回滚保存点: rollback to 保存点名字2 (此时保存点2后面操作的状态都将回滚直保存点2时样子)

// 开始查询空表
mysql> select * from t_x;
Empty set
 
// 开启事务
mysql> begin;
Query OK, 0 rows affected (0.01 sec)
 
// 插入第一条数据
mysql> insert into t_x value(1, '1');
Query OK, 1 row affected (0.01 sec)

// 设置保存点
mysql> savepoint a1;
Query OK, 0 rows affected (0.01 sec)
 
// 此时查询一条数据
mysql> select * from t_x;
+----+------+
| id | name |
+----+------+
|  1 | 1    |
+----+------+
1 row in set (0.01 sec)

// 插入第二条数据
mysql> insert into t_x value(2, '2');
Query OK, 1 row affected (0.01 sec)

// 设置保存点2
mysql> savepoint a2;
Query OK, 0 rows affected (0.01 sec)

// 查询两条数据
mysql> select * from t_x;
+----+------+
| id | name |
+----+------+
|  1 | 1    |
|  2 | 2    |
+----+------+
2 rows in set (0.01 sec)

// 插入第三条数据
mysql> insert into t_x value(3, '3');
Query OK, 1 row affected (0.01 sec)

// 共三条
mysql> select * from t_x;
+----+------+
| id | name |
+----+------+
|  1 | 1    |
|  2 | 2    |
|  3 | 3    |
+----+------+
3 rows in set (0.01 sec)

// 回滚到第一个保存点
mysql> rollback to a1;
Query OK, 0 rows affected (0.01 sec)

// 此时查询，只有第一个保存点时的一条数据
mysql> select * from t_x;
+----+------+
| id | name |
+----+------+
|  1 | 1    |
+----+------+
1 row in set (0.00 sec)

// 尝试回滚到第二个保存点, 出错
mysql> rollback to a2;
1305 - SAVEPOINT a2 does not exist
mysql>