title: django : How to write alias in queryset
body: <p>How can one write an alias for the column name in django query set.
  Would be useful for union-style combinations of two linked field to the same foreign model (for instance).</p>
  
  <p>for example in mysql :</p>
  
  <pre><code>select m as n, b as a from xyz
  </code></pre>
  
  <p>how can i do this in django query set ?</p>
  
  <pre><code>models.Table.objects.all().values('m', 'b')
  </code></pre>
  
  <p>Any help really appreciate it.</p>