ar_example.rb

require 'active_record'
ActiveRecord::Base.establish_connection :adapter => "sqlite3",
                                        :database => "dbfile" 

# Initialize the database schema
ActiveRecord::Base.connection.create_table :ducks do |t|
  t.string  :name
end

class Duck < ActiveRecord::Base
  validate do
    errors.add(:base, "Illegal duck name.") unless name[0] == 'D'
  end
end