Ruby on rails Rails有许多&；通过查询

我使用的是Rails 2.3，我有3个表，用于管理用户对建筑物的权限。mygroups表是用户和建筑物所属组的列表。mygroupsbuildings是建筑物及其关联组的列表。mygroupsusers是用户及其关联组的列表

create_table "mygroups", :force => true do |t|
  t.string   "name"
  t.integer  "user_id"
  t.string   "user_name"
  t.integer  "permissions"
end

create_table "mygroupbuildings", :force => true do |t|
  t.integer  "mygroup_id"
  t.integer  "building_id"
end

create_table "mygroupusers", :force => true do |t|
  t.integer  "mygroup_id"
  t.integer  "user_id"
  t.string   "user_name"
end

我想创建一个查询，以确定特定的用户id是否与特定的建筑id属于同一组

我已设置了以下关联：

class Mygroup < ActiveRecord::Base  
  has_many   :mygroupusers
  has_many   :mygroupbuildings
end

class Mygroubuilding < ActiveRecord::Base  
  belongs_to :mygroup
  has_many   :mygroupusers, :through => :mygroup
end

class Mygroupuser < ActiveRecord::Base
  belongs_to :mygroup
  has_many   :mygroupbuildings, :through => :mygroup
end

这给了我以下错误：

ActiveRecord:：语句无效（Mysql:：Error:on子句中的未知列“mygroups.mygroupid”：选择

mygroupusers

id

AS t0\u r0、

mygroupusers

mygroupid

AS t0\u r1、

mygroupusers

用户idAS t0\code>mygroupusersAS t0\u r3、

mygroupusers

de>作为t0\U r4，

mygroupusers

更新了作为t0\U r5，

mygroupbuildings

作为t1\U r0，

mygroupbuildings

mygroupbuildings

作为t1\u r1，

mygroupbuildings

作为t1\u r2，

mygroupbuildings

创建了作为t1\code>mygroupbuildings，

在（
mygroupusers
id
id
=
mygroups
mygroups\U id
）上（
mygroupbuildings
mygroupbuildings
id>）上的左侧外部连接
mygroupbuildings
）其中（mygroupbuildings.building_id='2'和mygroupusers.user_id='55'）：

谢谢

Nick，
这是如何设置查询以返回包含查询的用户id和建筑id的组：

Mygroup.find(:all,
             :include => [:mygroupbuildings, :mygroupusers],
             :conditions => ["mygroupbuildings.building_id = #{building.id} AND mygroupusers.user_id = #{current_user.user_id}"])      

Mygroup.find(:all,
             :include => [:mygroupbuildings, :mygroupusers],
             :conditions => ["mygroupbuildings.building_id = #{building.id} AND mygroupusers.user_id = #{current_user.user_id}"])