需要MySQL查詢幫助

Question

請幫我看看這個MySQL查詢。我已經堅持了很長時間。也許它需要一雙新鮮的眼睛。

兩個表：鎖和會議

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

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

我想刪除所有行鎖，其中會議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）;

從鎖 使用鎖上sessions.id = locks.session_id 加入會話刪除：

Answer 3

從鎖其中SESSION_ID在（select_id從會話其中USER_ID = 14）

Answer 4

的另一種方式，而不子查詢刪除 其中sessions.user_id = 14

Answer 5

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