(SELECT friend_id FROM user_friend_list WHERE user_id = '13' and
`friend_id` in(select user_id from user_friend_list where friend_id='13' and `is_delete` = 'No')
and is_delete = 'No')INTERSECT(SELECT friend_id FROM user_friend_list WHERE user_id = '20' and
friend_id in(select user_id from user_friend_list where friend_id='20' and is_delete = 'No')
and is_delete = 'No');
MySQL中没有INTERSECT运算符。尝试使用INNER JOIN代替:
SELECT friend_id FROM
(SELECT friend_id ...) T1
INNER JOIN
(SELECT friend_id ... ) T2
ON T1.friend_id = T2.friend_id;
MySQL不支持INTERSECT运算符。但是,您可以模拟INTERSECT运算符。
这里有一个在MYSQL中模拟INTERSECT的操作指南: