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#

步骤解析：

1. 找出属于Action分类的电影id，记为临时表tmp

   select
   fc.film_id
   from
   category as c,
   film_category as fc
   where
   c.category_id = fc.category_id and c.name = 'Action'

   此时，生成的临时表是多行单列，列的属性为film_id

2. 找出film中出现在tmp中的电影

   select
   f.title, f.description
   from
   film as f
   where 
   f.film_id in (
   select
   fc.film_id
   from
   category as c,
   film_category as fc
   where
   c.category_id = fc.category_id and c.name = 'Action'
   )