你那個查詢的條件明顯就不對

// tags表 `tags`.`title` = '聰明' AND `tags`.`title` = '勤奮' 這種數(shù)據(jù)根本就不存在

SELECT * FROM user

WHERE id IN (

    SELECT uid FROM tags WHERE title IN ('聰明', '勤奮') GROUP BY uid HAVING count(uid) = 2

);

select user.*,count(tags.uid)as num  from user left join tags on `user`.id = tags.uid 

where (`tags`.`title` = '聰明' OR `tags`.`title` = '勤奮') group by tags.uid 

having count(tags.uid) > 1