我有一个 Product 和 Creator 表，我还有一个名为 CreatorProduct 的表，它将创建者与产品连接起来。一个产品可以有很多创作者，一个创作者可以有很多产品。我想做的是找到有创作者的产品，有些产品可能没有创作者。
我已经编写了下面的代码，但是如何以更友好的方式编写它？这适用于我的 in rails 控制台，但是当我将其放入代码中时，我得到未定义的方法 `includes' for #
Product.find_by_sql("select * from Products where id in (select product_id from Creator_Products intersect select id from Products)")
谢谢！
I would probably just use the find function and use a similar where to what you have now:
Product.find(:all, :conditions => ["exists (select * from Creators where product_id = Products.Id)"])
Otherwise I guess with the way active record joins the data you could probably get the same by including the creator information (assuming you have the has_many set up) and then make sure that the creator information exists...
Product.find(params[:id],:include => [:Creator],:conditions => ["Creator.product_id!=null"])
If you don't have the relationships set up already you need to define then in your models:
class Product< ActiveRecord::Base
has_many :CreatorProduct
has_many :Creators, :through => :CreatorProduct