Question

Where can I find some information about building a query like this:

select
  SomeField1,
  (select count(distinct SomeField2) from SomeTable where SomeCondition) as SomeField3
from
  SomeTable2
where
  SomeCondition2

using Django ORM? It’s probably in the Django documentation somewhere but I can’t find it.

Answer 1

What’s the relationship of your two tables?

I guess you need the count,there is a code snippet without check,

SomeModel2.objects.annotate(new_field=Count('SomeField2', 
    distinct=True)).filter(condition=condition,
    another_condition=condition2).values('new_field', 'Somefield1')

See https://docs.djangoproject.com/en/dev/ref/models/querysets/#annotate and How to sort by annotated Count() in a related model in Django for more details.