Ruby on rails 如何使用Rails 3 activerecord编写此sql查询？

我试图使用Rails3ActiveRecord约定编写此查询

SELECT s.name, s.id FROM tripoli_schools_development.campus_programs cp 
  JOIN tripoli_schools_development.career_categories cc ON cp.career_category_id = cc.id 
  JOIN tripoli_schools_development.campuses c ON c.id = cp.campus_id 
  JOIN tripoli_schools_development.schools s ON s.id = c.school_id 
 WHERE cp.enabled = true and c.enabled = true and s.enabled = true and cc.id = 2 
 group by s.id order by s.name

以下是我的模型：

class CampusProgram < TripoliSchool
  belongs_to :career_category
  belongs_to :campus
end

class CareerCategory < TripoliSchool
  has_many :career_programs
  has_many :campus_programs
end

class Campus < TripoliSchool
  self.table_name = 'campuses'
  belongs_to :school
  has_many :campus_programs
end

class School < ActiveRecord::Base
  has_many :campuses, :class_name => "Campus"
  has_many :campus_programs, :through => :campuses
end

class CampusProgram“校园”
有许多：校园计划，：至=>：校园
结束

最重要的是

class TripoliSchool < ActiveRecord::Base
  self.abstract_class = true
  establish_connection "tripoli_schools_#{Rails.env}"
end

的黎波里学校

class

试试这个：

CompusProgram.select("shcools.name, shcools.id").joins([:career_categories, {:campuses => :schools}]).where("campus_programs.enabled = true and campuses.enabled = true and schools.enabled = true and career_categories.id = 2 ")

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我不确定，但你已经知道了。你可以在这里看到文件：。

多亏了杜吉和安托尼亚尔贝托，这一切才奏效

CampusProgram.select("schools.name, schools.id").joins(:career_category).joins(:campus => :school).where("campus_programs.enabled = true and campuses.enabled = true and schools.enabled = true and career_categories.id = 2").group("schools.id").order("schools.name")

这同样有效

CampusProgram.select("schools.name, schools.id").joins([:career_category, {:campus => :school}]).where("campus_programs.enabled = true and campuses.enabled = true and schools.enabled = true and career_categories.id = 2").group("schools.id").order("schools.name")

---

我发现这有一个语法错误：校园=>{:schools}]）。where（“校园计划：校园=>{:schools}似乎是错误所在。你能试试这个吗：加入（：职业分类）。加入（：校园=>{:schools}）

：校园=>{:schools}

不正确，应该是

：校园=>:schools

对不起，这是我的错误。试试这个：加入（[：职业分类，{：校园=>:schools}]）谢谢你的帮助…你让我开始学习，下面是工作原理：CampusProgram.select（“schools.name，schools.id”）.joins（：career\u category）。joins（：campus=>:school）。其中（“campus\u programs.enabled=true and campuses.enabled=true and schools.enabled=true and career\u categories.id=2”）.group（“schools.id”）.order（“学校名称”）