title: Product Index Using Django ORM
body: <p>I have a list of Products with a field called 'Title' and I have been trying to get a list of initial letters with not much luck. The closes I have is the following that dosn't work as 'Distinct' fails to work.</p>
  
  <pre><code>atoz = Product.objects.all().only('title').extra(select={'letter': "UPPER(SUBSTR(title,1,1))"}).distinct('letter')
  </code></pre>
  
  <p>I must be going wrong somewhere,
  I hope someone can help.</p>