如何查询多对多? [英] how to query many-to-many?

问题描述

在观看Rails教程中的ruby时，我发现了以下表结构.

I found the following table structures while I was watching ruby on rails tutorial.

table actors
id  int  11  primary key auto_increment
name  varchar  30

table movies
id  int  11  primary key auto_increment
name  varchar  30

table actors_movies
actor_id  int  11
movie_id  int  11

如何查询以选择演员所涉及的电影?

How do I make a query to select movies that an actor is involved in?

我不要求在Rails代码上使用红宝石.我想要实际的mysql查询字符串.

I am not asking for ruby on rails code. I want the actual mysql query string.

谢谢！

推荐答案

要考虑的一件事是，您将要加载作者对象(由于RoR模型)，因此使用ID就足够了:

one thing to consider is that you are going to load the author object (because of RoR models), so with the ID would be enough:

select movies.id, movies.name
from movies inner join actors_movies
on actors_movies.movie_id=movies.id
where actors_movies.actor_id=$actor_id

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