title: How do you update counter_cache in rails 3?
body: <p>I have a normal association in my Rails app:</p>
  
  <ul>
  <li><code>CustomerAccount has_many :orders</code></li>
  <li><code>Order belongs_to :customer_account</code></li>
  </ul>
  
  <p>Now, I've added a <code>:counter_cache =&gt; true</code> to the <code>belongs_to</code> statement and added the <code>orders_count</code> column to <code>CustomerAccount</code></p>
  
  <p>After the migration, every value in the <code>orders_count</code> column is 0. How do I update all these values to have the correct count?</p>