Mysql-事务,原子性操作

事物分为 自动（默认的）和手动（需开启事务）两种

-- 事务 start transaction;
    -- commite;  提交事务
    -- rollback; 回滚事务

create table if not exists account(
    id int primary key auto_increment,
    name varchar(14) not null,
    RMB int
);

insert into account(name,RMB) values('Which',1000),('Tj',998);

rollback; 进行一步操作后，可以撤回这个操作

-- 开始事务    手动事物

start transaction;

-- 事物操作
update account set RMB =RMB-992 where name = 'Which';
-- q  退出mysql(中断事务)
-- mysql -u name -p;  回到mysql　　　

-- 继续事务操作
    -- 回滚事务
    rollback;

+----+-------+------+   -- insert
| id | name  | RMB  |
+----+-------+------+
|  1 | Which |    8 |
|  2 | Tj    |  998 |
+----+-------+------+ 
-- update  |
--+-------+------+
| id | name  | RMB  |
+----+-------+------+
|  1 | Which |    8 |
|  2 | Tj    |  998 |
+----+-------+------+
-- rollback |     
+----+-------+------+       
| id | name  | RMB  |
+----+-------+------+
|  1 | Which |    8 |
|  2 | Tj    |  998 |
+----+-------+------+ 

commite:   自动提交

-- 事物操作
update account set RMB =RMB-992 where name = 'Which';
-- q  退出mysql(事务)
-- mysql -u name -p;  回到mysql

-- 实际上在这儿退出后，再回到account表，值并没有-992，但是再进行下一步操作后，992就转给Tj了。

 -- 继续事务操作 update account set RMB =RMB+992 where name = 'Tj';

-- insert   Which 1000,Tj 998
+----+-------+------+
| id | name  | RMB  |
+----+-------+------+
|  1 | Which | 1000 |
|  2 | Tj    |  998 |
+----+-------+------+
-- update   Which-992
+----+-------+------+
| id | name  | RMB  |
+----+-------+------+
|  1 | Which |    8 |
|  2 | Tj    |  998 |
+----+-------+------+
-- update   Tj+992
+----+-------+------+
| id | name  | RMB  |
+----+-------+------+
|  1 | Which |    8    |
|  2 | Tj       | 1990  |
+----+-------+------+

原子性操作：Innodb引擎支持事务

要么全部成功，要么全部失败