Difficult model.find

I can only think of doing it in Ruby:

  def other_users
    User.find(:all) - self.users
  end

there must be a more efficient way to do it via ActiveRecord
(therefore, only one query), something like

  def other_users
    User.find :all, :conditions => ["declaration_id <> ?", self.id]
  end

(or something like that, you get the idea, it's awfully not
abstracted).

Bye,

nachokb