rails多个连接和功能

Question

我有这个sql：

select al.name, date_trunc('day', rc.start_date) as d, min(rc.start_date)
from 
records rc inner join relations rl 
on rl.record_id=rc.id 
inner join
aliases al on rl.alias_id=al.id
where rc.user_id=2 and ( al.contact_id<>2 or al.contact_id is null)
group by al.name, d
order by d DESC

模特：

class Alias < ActiveRecord::Base
  belongs_to :contact
  has_many :relations, :dependent => :destroy
  has_many :records, :through => :relations 
  belongs_to :user
end

class Record < ActiveRecord::Base
  has_many :relations, :dependent => :destroy
  has_many :aliases, :through => :relations
  belongs_to :user
end

class Relation < ActiveRecord::Base
  belongs_to :record
  belongs_to :alias
end

class Contact < ActiveRecord::Base
  has_many :aliases
  belongs_to :user
end

class User < ActiveRecord::Base  
  has_many :aliases
  has_many :contacts
  has_many :records
end

如何编写以rails方式呈现的sql查询？