rubyからPostgreSQLに接続するためのコード

gistfile1.txt

require 'pg'
require "active_record"

ActiveRecord::Base.establish_connection(
  :adapter=>"postgresql",
  :database =>"postgres",
  :username=>"postgres",
  :password=>"password",
)

class User < ActiveRecord::Base
  self.table_name = 'users'
end

p User.all