MySQL 如何查询多对多？
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how to query many-to-many?
提问by Moon
I found the following table structures while I was watching ruby on rails tutorial.
我在看 ruby on rails 教程时发现了以下表格结构。
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
How do I make a query to select movies that an actor is involved in?
如何进行查询以选择演员参与的电影？
I am not asking for ruby on rails code. I want the actual mysql query string.
我不是要求 ruby on rails 代码。我想要实际的 mysql 查询字符串。
Thank you!
谢谢！
采纳答案by fesja
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:
需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：
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
回答by Andy White
Maybe something like this:
也许是这样的：
select m.name
from movies m
inner join actors_movies am on m.id = am.movie_id
inner join actors a on am.actor_id = a.id
where a.name = 'Christopher Walken'
回答by Justin Ethier
Simple, just use the combined table to join the movie/actor tables:
很简单，只需使用组合表加入电影/演员表：
Select m.name
From actors a
Inner Join actors_movies am On am.actor_id = a.id
Inner Join movies m On m.id = am.movie_id
Where a.name = @your_actor
回答by razenha
select m.* from movies m
inner join actors_movies am on am.movie_id = m.id
inner join actors a on a.id = am.actor_id
where a.someField = somevalue
