title: How to use Joined table in django queryset
body: <p>i was join two table and i want to get field in joined model class</p>
  
  <pre><code>school_name_list = Students.objects.select_related('School').values('school_name')
  </code></pre>
  
  <p>but this code raise </p>
  
  <pre><code>django.core.exceptions.FieldError: Cannot resolve keyword 'school_name' into field``
  </code></pre>
  
  <p>how can i solve it?</p>