How to execute a GROUP BY … COUNT or SUM in Django ORM?

后端未结

关注

 1  1820

面向向阳花

Prologue:

This is a question arising often in SO:

Django Models Group By
Django equivalent for count and group by
Ho

相关标签:

1条回答

星月不相逢

2020-11-27 18:30

We can perform a GROUP BY ... COUNT or a GROUP BY ... SUM SQL equivalent queries on Django ORM, with the use of annotate(), values(), the django.db.models's Count and Sum methods respectfully and optionally the order_by() method:

GROUP BY ... COUNT:

from django.db.models import Count

result = Books.objects.values('author')
                      .order_by('author')
                      .annotate(count=Count('author'))

Now result contains a dictionary with two keys: author and count:

  author    | count
------------|-------
 OneAuthor  |   5
OtherAuthor |   2
   ...      |  ...

GROUP BY ... SUM:

from django.db.models import Sum

 result = Books.objects.values('author')
                       .order_by('author')
                       .annotate(total_price=Sum('price'))

Now result contains a dictionary with two columns: author and total_price:

  author    | total_price
------------|-------------
 OneAuthor  |    100.35
OtherAuthor |     50.00
    ...     |      ...

0 讨论(0)