Listing 3. database.rb

require 'rubygems'
require 'active_record'

class Customer < ActiveRecord::Base
  set_table_name 'customer'
  has_one :address
end

class Address < ActiveRecord::Base
  set_table_name 'address'
  belongs_to :customer
  has_one :location
end

class Location < ActiveRecord::Base
  belongs_to :address
end

ActiveRecord::Base.establish_connection(
  :adapter => 'mysql',
  :database => 'customers'
)