删除查询sql

Question

我正在尝试使用以下方法删除与该会话相关的会话和练习：

$delete_session =

"DELETE FROM sessions, exercises 
USING sessions 
INNER JOIN exercises 
ON sessions.session_id = exercises.session_id 
WHERE sessions.session_id= '$delete_id'";

如果有与会话相关联的练习但如果会话没有练习则不会触发上述查询。

我可以一起使用上面的查询吗？

"DELETE FROM sessions WHERE session_id= '$delete_id'";

我怎么能得到会话将删除与否链接的练习？

Answer 1

你应该使用LEFT INNER JOIN

$delete_session =
"DELETE FROM sessions, exercises 
USING sessions 
LEFT INNER JOIN exercises 
ON sessions.session_id = exercises.session_id 
WHERE sessions.session_id= '$delete_id'";