from django.db import models

class TestModel(models.Model):
    f = models.IntegerField(null = True, blank = True)

# from django.db import connection
# print TestModel.objects.exclude(f=5)
# print connection.queries
# [{'time': '0.002', 'sql': 'SELECT "t_testmodel"."id", "t_testmodel"."f" FROM "t_testmodel" WHERE NOT (("t_testmodel"."f" = 5  AND "t_testmodel"."f" IS NOT NULL)) LIMIT 21'}]