查詢中有什麼問題

Question

我在下面查詢...

有沒有什麼問題呢？

delete from user_role 
WHERE user_id in (
    select u.user_id from user u, user_role ur 
    where u.USER_ID=ur.USER_ID and ur.ROLE_ID=4 and u.USER_ID not in (
     select user_id from referrers)); 

Answer 1

正如在手冊中規定的DELETE Syntax：

Currently, you cannot delete from a table and select from the same table in a subquery.

可以代替使用DELETE和join在一起的表中的多個數據表的形式：

DELETE user_role 
FROM user_role 
    INNER JOIN user_id USING (USER_ID) 
    LEFT JOIN referrers USING (USER_ID) 
WHERE user_role.ROLE_ID = 4 AND referrers.USER_ID IS NULL