104 lines
2.4 KiB
Markdown
104 lines
2.4 KiB
Markdown
回滚事务
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=========================
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回滚一个事务指将事务的修改全部撤销。可以回滚当前整个未提交事务，也可以回滚到事务中任意一个保存点。如果要回滚到某个保存点，必须结合使用 ROLLBACK 和 TO SAVEPOINT 语句。
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如果回滚整个事务：
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* 事务会结束。
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* 所有的修改会被丢弃。
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* 清除所有保存点。
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* 释放事务持有的所有锁。
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如果回滚到某个保存点：
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* 事务不会结束。
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* 保存点之前的修改被保留，保存点之后的修改被丢弃。
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* 清除保存点之后的保存点（不包括保存点自身）。
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* 释放保存点之后事务持有的所有锁。
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示例：ROLLBACK 回滚事务的全部修改
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------------------------------
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```javascript
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obclient> select * from t_insert;
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+----+------+-------+---------------------+
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| ID | NAME | VALUE | GMT_CREATE |
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+----+------+-------+---------------------+
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| 1 | CN | 10001 | 2020-04-02 17:52:31 |
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| 2 | US | 10002 | 2020-04-02 17:52:38 |
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| 3 | EN | 10003 | 2020-04-02 17:52:38 |
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+----+------+-------+---------------------+
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3 rows in set (0.00 sec)
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obclient> begin;
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Query OK, 0 rows affected (0.00 sec)
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obclient> insert into t_insert(id, name, value) values(4,'JP',10004);
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Query OK, 1 row affected (0.00 sec)
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obclient> insert into t_insert(id, name, value) values(5,'FR',10005),(6,'RU',10006);
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Query OK, 2 rows affected (0.00 sec)
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Records: 2 Duplicates: 0 Warnings: 0
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obclient> select * from t_insert;
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+----+------+-------+---------------------+
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| ID | NAME | VALUE | GMT_CREATE |
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+----+------+-------+---------------------+
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| 1 | CN | 10001 | 2020-04-02 17:52:31 |
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| 2 | US | 10002 | 2020-04-02 17:52:38 |
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| 3 | EN | 10003 | 2020-04-02 17:52:38 |
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| 4 | JP | NULL | 2020-04-02 17:53:34 |
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| 5 | FR | 10005 | 2020-04-02 17:54:53 |
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| 6 | RU | 10006 | 2020-04-02 17:54:53 |
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+----+------+-------+---------------------+
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6 rows in set (0.00 sec)
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obclient> rollback;
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Query OK, 0 rows affected (0.00 sec)
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obclient> select * from t_insert;
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+----+------+-------+---------------------+
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| ID | NAME | VALUE | GMT_CREATE |
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+----+------+-------+---------------------+
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| 1 | CN | 10001 | 2020-04-02 17:52:31 |
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| 2 | US | 10002 | 2020-04-02 17:52:38 |
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| 3 | EN | 10003 | 2020-04-02 17:52:38 |
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+----+------+-------+---------------------+
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3 rows in set (0.00 sec)
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```
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