1.分析
子查询关键是建立好表与表之间的联系,
where和子查询对等。

2.代码
# SELECT f.title, f.description
# FROM film AS f, category AS c, film_category AS fc
# WHERE f.film_id = fc.film_id
# and c.category_id = fc.category_id
# and c.name = "Action"

SELECT f.title, f.description
FROM film AS f
WHERE f.film_id in (select fc.film_id from film_category as fc 
                   where fc.category_id in(select c.category_id from category as c
                                              where c.name = "Action"))