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                **1. 事務控制語句** * `BEGIN` 或 `START TRANSACTION` 顯式地開啟一個事務; * `COMMIT` 也可以使用 `COMMIT WORK`,不過二者是等價的。提交事務,并使已對數據庫進行的所有修改成為永久性的; * `ROLLBACK` 也可以使用 `ROLLBACK WORK`,不過二者是等價的。回滾會結束用戶的事務,并撤銷正在進行的所有未提交的修改; * `SAVEPOINT identifier_name`,`SAVEPOINT` 允許在事務中創建一個保存點,一個事務中可以有多個 `SAVEPOINT`。保存點在執行`COMMIT`,或`ROLLBACK`后自動被釋放; * `RELEASE SAVEPOINT identifier_name` 刪除一個事務的保存點,當沒有指定的保存點時,執行該語句會拋出一個異常; * `ROLLBACK TO identifier_name` 把事務回滾到保存點; * `SET TRANSACTION` 用來設置事務的隔離級別。InnoDB 存儲引擎提供事務的隔離級別有`READ UNCOMMITTED`、`READ COMMITTED`、`REPEATABLE READ` 和 `SERIALIZABLE`。 **2. 開啟事務的方式** 1、用 `BEGIN`, `ROLLBACK`, `COMMIT`來實現 ``` BEGIN 開始一個事務 ROLLBACK 事務回滾 COMMIT 事務確認 ``` 2、直接用 `SET` 來改變 MySQL 的自動提交模式; ``` SET AUTOCOMMIT=0 禁止自動提交(開啟事務) SET AUTOCOMMIT=1 開啟自動提交(關閉事務) ``` **3. 案例演示** ```sql BEGIN; #一些insert/delete/update語句 insert into learn_mysql.student(name, age, sex) values('張三',20, '男'); insert into learn_mysql.student(name, age, sex) values('李四',21, '男'); insert into learn_mysql.student(name, age, sex) values('王五',22, '男'); #回滾,對數據庫沒有任何影響 ROLLBACK; COMMIT; SET AUTOCOMMIT=0; #一些insert/delete/update語句 insert into learn_mysql.student(name, age, sex) values('張三',20, '男'); insert into learn_mysql.student(name, age, sex) values('李四',21, '男'); insert into learn_mysql.student(name, age, sex) values('王五',22, '男'); #回滾,對數據庫沒有任何影響 ROLLBACK; COMMIT; SET AUTOCOMMIT=0; #一些insert/delete/update語句 insert into learn_mysql.student(name, age, sex) values('張三',20, '男'); insert into learn_mysql.student(name, age, sex) values('李四',21, '男'); insert into learn_mysql.student(name, age, sex) values('王五',22, '男'); #不提交,對數據庫沒有任何影響 #COMMIT; BEGIN; #一些insert/delete/update語句 insert into learn_mysql.student(name, age, sex) values('張三',20, '男'); #定義保存點save_point_001 SAVEPOINT save_point_001; insert into learn_mysql.student(name, age, sex) values('李四',21, '男'); insert into learn_mysql.student(name, age, sex) values('王五',22, '男'); #回滾到保存點save_point_001 ROLLBACK TO save_point_001; #刪除保存點save_point_001 RELEASE SAVEPOINT save_point_001; ROLLBACK; COMMIT; ```
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