Question

I have

class Autosalon < ActiveRecord::Base
  has_many :autos
end

class Auto < ActiveRecord::Base
  belongs_to :autosalon
end

autosalon has flag active=1 and date of registration, auto has flag active=1

How get all autos with active flag in autosalons with active flag without JOIN?

Answer 1

Without any joins/includes, you could use a SQL in query:

Auto.where(:active => 1).where("autosalon_id in (select id from autosalons where active=1)")