需要MySQL查询帮助

Question

请帮我看看这个MySQL查询。我已经坚持了很长时间。也许它需要一双新鲜的眼睛。

两个表：锁和会议

locks 
-------------- 
id session_id 
-------------- 
1 sajf4$Jf9422jd 
2 2jf*4j2okg9092 
3 J8j4j4ffss93o2 
------------------ 

sessions 
------------------------- 
id    user_id 
------------------------- 
sajf4$Jf9422jd 14 
J8j4j4ffss93o2 14 
2jf*4j2okg9092 21 
------------------------- 

我想删除所有行锁，其中会议USER_ID = 14

Answer 1

DELETE FROM locks 
WHERE session_id IN (SELECT id FROM sessions WHERE user_id = 14) 

Answer 2

DELETE FROM locks WHERE session_id =（SELECT id FROM sessions WHERE user_id = 14）;

从锁 使用锁上sessions.id = locks.session_id 加入会话删除：

Answer 3

从锁其中SESSION_ID在（select_id从会话其中USER_ID = 14）

Answer 4

的另一种方式，而不子查询删除 其中sessions.user_id = 14

Answer 5

DELETE locks, sessions FROM locks INNER JOIN sessions WHERE locks.session_id=sessions.id;