ActiveRecord without rails.

gistfile1.rb

require "active_record"
require "sqlite3"

ActiveRecord::Base.establish_connection(
  :adapter  => 'sqlite3',
  :database => 'ejemplo',
  :host     => 'localhost')

ActiveRecord::Schema.define(:version => 0) do

  create_table "categories", :force => true do |t|
    t.string   "name"
    t.datetime "created_at", :null => false
    t.datetime "updated_at", :null => false
  end
end

class Category < ActiveRecord::Base
  attr_accessible :name
end

cat = Category.create(name: 'Un nombre')

puts "Categoria nueva: #{cat.name}"
puts "Creado el dia: #{cat.created_at}"