For demonstration purposes, the following examples use a very simple Django model. The same ORM queries can be applied to more complex models in real projects.

class Number(models.Model):
    number = models.IntegerField(null=True)

🔗 List of content:

• Excluding specific values
• Find objects with NULL values
• Find duplicated entries

Excluding specific values

Use this query when you want to remove specific values from a queryset.

numbers = Number.objects.exclude(number__in=[0,4,6,8,9])

Find objects with NULL values

Returns objects where the field has no value stored in the database.

numbers = Number.objects.filter(number__isnull=True)

Find duplicated entries

Identifies values that appear more than once in the database.

from django.db.models import Count

duplicates = (
    Number.objects
    .values("number")
    .annotate(total=Count("number"))
    .filter(total__gt=1)
)