# Advanced QuerySets (Django)

> Lookups, Q objects, F expressions, aggregation, annotations, select_related, prefetch_related

- 25 interview questions
- Mid-Level
- [Interview Questions: Django](https://sharpskill.dev/en/technologies/django/interview-questions.md)

## 1. Which lookup allows filtering objects where a field contains a specific string, case-insensitively?

**Answer**

The icontains lookup performs a case-insensitive search to check if a field contains a substring. The 'i' prefix in icontains indicates that the comparison ignores case, which is useful for user searches where case may vary.

## 2. What is the main difference between select_related and prefetch_related?

**Answer**

select_related uses a SQL JOIN to retrieve related objects in a single query, but only works for ForeignKey and OneToOne relationships. prefetch_related performs separate queries then links objects in Python, making it suitable for ManyToMany and reverse ForeignKey relationships.

## 3. Which Django object allows combining filter conditions with an OR operator?

**Answer**

Q objects allow building complex queries by combining conditions with | (OR), & (AND) and ~ (NOT) operators. Without Q objects, chained filter() calls only apply AND conditions, making it impossible to create OR queries directly.

## 22 more questions available

- What is the main advantage of using F() expressions instead of Python values in an update?
- Which aggregation method returns a dictionary with calculated values instead of a QuerySet?

Sign up for free: https://sharpskill.dev/en/login

## Other Django interview topics

- [Python Basics](https://sharpskill.dev/en/technologies/django/interview-questions/python-basics.md): 25 questions, Junior
- [Python OOP](https://sharpskill.dev/en/technologies/django/interview-questions/python-oop.md): 20 questions, Junior
- [Django Fundamentals](https://sharpskill.dev/en/technologies/django/interview-questions/django-fundamentals.md): 20 questions, Junior
- [Django Models - Basics](https://sharpskill.dev/en/technologies/django/interview-questions/django-models-basics.md): 22 questions, Junior
- [Django Views](https://sharpskill.dev/en/technologies/django/interview-questions/django-views.md): 20 questions, Junior
- [Django Templates](https://sharpskill.dev/en/technologies/django/interview-questions/django-templates.md): 18 questions, Junior
- [Django Forms](https://sharpskill.dev/en/technologies/django/interview-questions/django-forms.md): 22 questions, Mid-Level
- [Django Authentication](https://sharpskill.dev/en/technologies/django/interview-questions/django-authentication.md): 22 questions, Mid-Level
- [Django Middleware](https://sharpskill.dev/en/technologies/django/interview-questions/django-middleware.md): 18 questions, Mid-Level
- [Django Admin](https://sharpskill.dev/en/technologies/django/interview-questions/django-admin.md): 20 questions, Mid-Level
- [Django REST Framework](https://sharpskill.dev/en/technologies/django/interview-questions/django-rest-framework.md): 30 questions, Mid-Level
- [Django Signals](https://sharpskill.dev/en/technologies/django/interview-questions/django-signals.md): 18 questions, Mid-Level
- [File Upload](https://sharpskill.dev/en/technologies/django/interview-questions/django-file-upload.md): 20 questions, Mid-Level
- [Django Caching](https://sharpskill.dev/en/technologies/django/interview-questions/django-caching.md): 20 questions, Mid-Level
- [Django Sessions](https://sharpskill.dev/en/technologies/django/interview-questions/django-sessions.md): 18 questions, Mid-Level
- [Django Email](https://sharpskill.dev/en/technologies/django/interview-questions/django-email.md): 18 questions, Mid-Level
- [Django Testing](https://sharpskill.dev/en/technologies/django/interview-questions/django-testing.md): 22 questions, Mid-Level
- [Django Security](https://sharpskill.dev/en/technologies/django/interview-questions/django-security.md): 22 questions, Mid-Level
- [Django Deployment](https://sharpskill.dev/en/technologies/django/interview-questions/django-deployment.md): 24 questions, Mid-Level
- [Advanced Django ORM](https://sharpskill.dev/en/technologies/django/interview-questions/django-orm-advanced.md): 28 questions, Senior
- [Django Performance](https://sharpskill.dev/en/technologies/django/interview-questions/django-performance.md): 24 questions, Senior
- [Django & Celery](https://sharpskill.dev/en/technologies/django/interview-questions/django-celery.md): 22 questions, Senior
- [Django Channels](https://sharpskill.dev/en/technologies/django/interview-questions/django-channels.md): 24 questions, Senior
- [Django & GraphQL](https://sharpskill.dev/en/technologies/django/interview-questions/django-graphql.md): 24 questions, Senior
- [Django & Docker](https://sharpskill.dev/en/technologies/django/interview-questions/django-docker.md): 20 questions, Senior
- [Django in Microservices Ecosystem](https://sharpskill.dev/en/technologies/django/interview-questions/django-microservices.md): 24 questions, Senior
- [Custom Django Commands](https://sharpskill.dev/en/technologies/django/interview-questions/django-custom-commands.md): 18 questions, Senior
- [Django Internationalization](https://sharpskill.dev/en/technologies/django/interview-questions/django-internationalization.md): 20 questions, Senior
- [Django Design Patterns](https://sharpskill.dev/en/technologies/django/interview-questions/django-design-patterns.md): 24 questions, Senior
- [Django Async & ASGI](https://sharpskill.dev/en/technologies/django/interview-questions/django-async-asgi.md): 26 questions, Senior
- [Settings & Production Configuration](https://sharpskill.dev/en/technologies/django/interview-questions/django-settings-configuration.md): 22 questions, Senior
- [Observability & Monitoring](https://sharpskill.dev/en/technologies/django/interview-questions/django-observability.md): 24 questions, Senior

---

Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack.
HTML version of this page: https://sharpskill.dev/en/technologies/django/interview-questions/django-querysets