题解 | #使用子查询的方式找出属于Action分类的所有电影对应的title,description#

select title,description from film as fi
where fi.film_id in-- 结果是一列数据，要用in
  (select fc.film_id from film_category as fc where category_id in -- 得到电影编码=1，2
   (select c.category_id from category as c where name='action'))-- 得到类型编码=1