title: Mysql2::Error: Column 'created_at' in order clause is ambiguous
body: <p>I have the following query that is working correctly </p>
  
  <pre><code>ObjectItem.find(:all, :include =&gt; :object_groups, :conditions =&gt;  "object_items.description LIKE '%#{search}%' OR object_groups.description LIKE '%#{search}%'", :order =&gt; 'object_items.created_at DESC')
  </code></pre>
  
  <p>But doing query this way is now deprecated so i'm trying to change to this form</p>
  
  <pre><code>ObjectItem.order('object_items.created_at DESC').includes(:object_groups).where("object_items.description LIKE '%#{search}%' OR object_groups.description LIKE '%#{search}%'")
  </code></pre>
  
  <p>But i'm getting the following error:</p>
  
  <pre><code>Mysql2::Error: Column created_at in order clause is ambiguous: SELECT  DISTINCT `object_items`.id FROM `object_items` LEFT OUTER JOIN `object_groups_object_items` ON `object_groups_object_items`.`object_item_id` = `object_items`.`id` LEFT OUTER JOIN `object_groups` ON `object_groups`.`id` = `object_groups_object_items`.`object_group_id` WHERE (object_items.description LIKE '%%' OR object_groups.description LIKE '%%') ORDER BY object_items.created_at DESC, created_at DESC  LIMIT 20 OFFSET 0
  </code></pre>