MySQL:事务处理

事务处理用来维护数据库的完整性，用来管理成批执行的MySQL操作。下面分别举例说明怎么开启事务，进行回滚，提交和使用保留点。

1、开启事务

START TRANSACTION

2、使用回滚Rollback

例1：删除表的所有行再回滚

SELECT * FROM ordersnew;
START TRANSACTION;
DELETE FROM ordersnew;
SELECT * FROM ordersnew;
ROLLBACK
SELECT * FROM ordersnew;

3、提交事务commit

START TRANSACTION
DELETE FROM orderitems WHERE order_num=20010;
DELETE FROM orders WHERE order_num=20010;
COMMIT;

4、使用保留点

起一个默认的名字 如del1，可以回滚到创建的保留点，提交时保留点自动释放，也可以release savepoint释放掉

SELECT * FROM ordersnew;
START TRANSACTION;
INSERT INTO ordersnew (odate,cui)VALUES ('2019-01-03 20:00:00',10001)

SAVEPOINT del1;
DELETE FROM ordersnew;
SELECT * FROM ordersnew;
ROLLBACK TO del1;
SELECT * FROM ordersnew;