Mysql 有用户表、标签表，如何查询同时拥有某几个标签的用户？

Question

Mysql 有用户表、标签表，如何查询同时拥有某几个标签的用户。

Answer 1

你那个查询的条件明显就不对

// tags表 `tags`.`title` = '聪明' AND `tags`.`title` = '勤奋' 这种数据根本就不存在

SELECT * FROM user

WHERE id IN (

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

);

Answer 2

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

where (`tags`.`title` = '聪明' OR `tags`.`title` = '勤奋') group by tags.uid 

having count(tags.uid) > 1