SQL29题解：使用join查询方式找出没有分类的电影id以及名称

此类问题很明显采用外连接+where IS NULL过滤，或者内连接 NOT IN 取补集
方案1：外连接+where

SELECT f.film_id AS '电影id',f.title AS '名称'
    FROM film f
    LEFT JOIN film_category fc
    ON f.film_id = fc.film_id
    WHERE fc.category_id IS NULL

方案2：找出有分类的电影film_id的集合，NOT IN 反转得未分类电影作为where子查询

SELECT film_id AS '电影id',title AS '名称'
    FROM film
    WHERE film_id NOT IN (SELECT f.film_id FROM film f
                            INNER JOIN film_category fc
                            ON f.film_id = fc.film_id);