mysql怎么加行锁？

START TRANSACTION;  #加事务

SELECT UserID,Password,Age FROM AccountsDB.Accounts_InFo    WHERE Accounts = 'hello2' FOR UPDATE;  #加锁

select SLEEP(5);  # 睡眠

COMMIT; #提交

START TRANSACTION; 

SELECT UserID,Password,Age FROM AccountsDB.Accounts_InFo    WHERE Accounts = 'hello2' FOR UPDATE;

COMMIT;