title: Rails - migrations - change_column_default
body: <p>I wish to change the default of an integer in my database via migrations</p>
  
  <pre><code>class ChangeColumnDefault &lt; ActiveRecord::Migration
    def self.up
      change_column_default(:persons, :age, 0)
    end
  end
  </code></pre>
  
  <p>I have also tried:</p>
  
  <pre><code>class ChangeColumnDefault &lt; ActiveRecord::Migration
        def change
          change_column_default(:persons, :age, 0)
        end
      end
  </code></pre>
  
  <p>And I just run the migration by:</p>
  
  <pre><code>rake db:migrate VERSION=20120822182554_change_column_default.rb
  </code></pre>
  
  <p>No errors are displayed in the terminal, and i can see no changes in my schema.rb</p>
  
  <p>Any ideas/hints??</p>