title: Django queries when Joining the same table on itself
body: <p>I find at my job I often have to join the same table on itself, partly because I have no control of the DB design, and partly because things are wanted pretty custom most of the time.</p>
  
  <pre><code>Select distinct t.label, z.dupCount
      From optevents t
      Join
        (select label, Count(*) dupCount
            from optevents 
            group By label
            Having Count(*) &gt; 1) z
      On z.label = t.label
      where t.campaignId = 100
      order By dupCount Desc
  </code></pre>
  
  <p>I'm curious how I can convert this to a Django ORM lookup?</p>
  
  <p>The Model definition is pretty simple, no foreign keys at all.</p>