题解 | #查找在职员工自入职以来的薪水涨幅情况#
查找描述信息中包含robot的电影对应的分类名称以及电影数目，而且还需要该分类对应电影数量>=5部
http://www.nowcoder.com/practice/3a303a39cc40489b99a7e1867e6507c5
select c.name,count(a.film_id) from film a inner join film_category b on a.film_id = b.film_id inner join category c on c.category_id = b.category_id where a.description like '%robot%' and c.category_id in (SELECT category_id FROM film_category GROUP BY category_id HAVING COUNT(film_id) >= 5);首先能用联结尽量避免用子查询
