本题中有三张表:电影信息表film、类别表category、电影分类表film_category; 可以使用左连接(左边有的,右边没有的则为空null) 解题代码: 方法1: select f.film_id,f.title from film f left join film_category fc on f.film_id=fc.film_id where f.film_id not in (select film_id from film_category); 方法2: select f.film_id,f.title from film f left join film_category fc on f.film_id=fc.film_id where fc.category_id is null;