title: Rails adding many to many association?
body: <p>i have a "Question" model and a "Tag" model. I added a many-to-many association to these two model.
  that's what i have now :</p>
  
  <pre><code>class Question &lt; ActiveRecord::Base
    attr_accessible :content, :score, :title
     has_and_belongs_to_many :tags
  
  end
  
  class Tag &lt; ActiveRecord::Base
    attr_accessible :description, :name
     has_and_belongs_to_many :questions
  end
  </code></pre>
  
  <p>What should i do to update the database and the controllers ?</p>
  
  <p>thanks</p>