When preparing for a software development or database-related interview, mastering ADO.NET Entity Framework interview questions is crucial.
In this detailed guide, you’ll find the top questions often asked — complete with crisp explanations.
Let’s dive right into it! 🚀
📌 1. What is the difference between ADO.NET and Entity Framework?
- ADO.NET requires manual SQL coding and database operations.
- Entity Framework (EF) abstracts database operations using an ORM approach, allowing you to interact with your database using .NET objects.
📌 2. What is Entity Framework?
Entity Framework (EF) is an open-source ORM framework for .NET applications. It simplifies data access by allowing developers to work with databases using C# or VB.NET objects.
📌 3. What is DbContext in Entity Framework?
DbContext is a primary class that manages database connections and is responsible for querying and saving data.
📌 4. What are the different approaches in Entity Framework?
- Database First
- Model First
- Code First
Each approach caters to different project requirements.
📌 5. What is Code First Approach in EF?
In Code First, you create entity classes first, and EF generates the database schema based on these classes.
📌 6. What is Database First Approach?
Here, you design your database first, and Entity Framework generates models and context classes from the database.
📌 7. What is Model First Approach?
Model First allows you to design a visual model in the EF designer, which then generates the database schema and classes.
📌 8. What is lazy loading in Entity Framework?
Lazy loading delays the loading of related data until it’s actually accessed for the first time.
📌 9. What is eager loading in EF?
Eager loading fetches related entities as part of the initial database query, reducing the number of queries.
csharpCopyEditvar student = context.Students.Include(s => s.Courses).ToList();
📌 10. What is explicit loading?
Explicit loading is manually loading related entities using .Load() method.
csharpCopyEditcontext.Entry(student).Reference(s => s.Course).Load();
📌 11. What is the use of DbSet in EF?
DbSet<TEntity> represents a collection for a specific entity type in the DbContext and allows CRUD operations on that entity.
📌 12. How does Entity Framework handle concurrency?
EF can detect changes made by multiple users to the same data and throw a DbUpdateConcurrencyException, allowing you to resolve conflicts.
📌 13. How do migrations work in Entity Framework?
Migrations manage changes to your database schema over time, allowing version control of the database.
Commands:
bashCopyEditAdd-Migration MigrationName
Update-Database
📌 14. What is a navigation property in EF?
A navigation property in EF links one entity to another. For example, an Order entity might have a navigation property called Customer.
📌 15. What is the difference between LINQ to SQL and Entity Framework?
- LINQ to SQL only works with SQL Server.
- Entity Framework works with multiple databases like SQL Server, MySQL, PostgreSQL, and more.
📌 16. What is AsNoTracking() in EF?
AsNoTracking() improves performance by telling EF not to track changes on the returned entities.
csharpCopyEditvar employees = context.Employees.AsNoTracking().ToList();
📌 17. How to enable or disable lazy loading in EF?
You can configure it in the DbContext constructor:
csharpCopyEditthis.Configuration.LazyLoadingEnabled = false;
📌 18. What are complex types in Entity Framework?
Complex types are non-scalar properties of an entity that do not have their own identity (i.e., no primary key).
📌 19. How does Entity Framework track changes?
EF maintains an internal change tracker that monitors entity states: Added, Modified, Deleted, or Unchanged.
📌 20. How can you optimize performance in Entity Framework?
- Use
AsNoTracking()for read-only operations. - Minimize round trips to the database.
- Use batch updates when possible.
- Apply proper indexing at the database level.
- Avoid N+1 query problems by using eager loading.
📌 21. What is TPH (Table Per Hierarchy) in EF?
TPH is an inheritance mapping strategy where a single table is used to maintain data for all entity types in a hierarchy using a discriminator column.
📚 People Also Ask (Bonus FAQs)
✅ What is the difference between ADO.NET and Entity Framework?
ADO.NET is a low-level technology requiring manual SQL management, whereas EF abstracts database operations through objects.
✅ What is DbContext in Entity Framework?
It’s the main class for database interactions, entity tracking, and saving changes in EF.
✅ What is lazy loading in Entity Framework?
Lazy loading automatically loads related entities only when the navigation property is accessed.
🔥 Conclusion
Mastering these ADO.NET Entity Framework interview questions will put you in a strong position for your next technical interview. Focus not only on theoretical knowledge but also on practical implementation to stand out.
Remember, practice real-world scenarios and optimize queries wherever possible for better understanding.
Good luck! 🚀