Entity Framework is an Object-Relational Mapping (ORM) framework developed by Microsoft. It is a popular tool used in .NET applications for connecting and interacting with databases. Entity Framework simplifies the process of working with databases by providing an abstraction layer between the application and the database, allowing developers to work with database entities as regular .NET objects.

With Entity Framework, developers can define entity classes that represent database tables, and these entities are automatically mapped to the corresponding database tables. This eliminates the need to write complex SQL queries manually, as Entity Framework handles the communication with the database and performs CRUD (Create, Read, Update, Delete) operations on the entities.

Entity Framework Interview Questions

1. What is Entity Framework?

Entity Framework is an Object-Relational Mapping (ORM) framework that enables developers to work with relational databases using object-oriented code.

2. What are the key components of Entity Framework?

The key components of Entity Framework are the ObjectContext (or DbContext in newer versions), entities, associations, and mapping.

3. What is the difference between DbContext and ObjectContext in Entity Framework?

DbContext is a simplified version of ObjectContext introduced in Entity Framework 4.1. It provides a simpler API and is the preferred choice for new applications.

4. What are the different approaches to database initialization in Entity Framework?

Entity Framework supports three approaches for database initialization: CreateDatabaseIfNotExists, DropCreateDatabaseIfModelChanges, and DropCreateDatabaseAlways.

5. What is Code First approach in Entity Framework?

Code First is an approach in Entity Framework where the database is generated from the code by defining entities and their relationships, and then letting Entity Framework create the database schema.

6. Explain the steps involved in Code First migration.

Code First migration involves enabling migrations, creating a migration, applying a migration, and updating the database schema using the migration history.

7. What is Lazy Loading in Entity Framework?

Lazy Loading is a feature in Entity Framework that enables related entities to be automatically loaded from the database when accessed for the first time.

8. What is Eager Loading in Entity Framework?

Eager Loading is a technique in Entity Framework where related entities are loaded from the database along with the main entity in a single query, using the Include method.

9. How can you disable Lazy Loading in Entity Framework?

Lazy Loading can be disabled by setting the LazyLoadingEnabled property to false in the DbContext or ObjectContext.

10. What is the purpose of the AsNoTracking method in Entity Framework?

The AsNoTracking method in Entity Framework disables change tracking for the queried entities, resulting in improved performance when entities are read-only.

11. What is the difference between DbSet and IQueryable in Entity Framework?

DbSet represents a collection of entities of a specific type, while IQueryable represents a query that can be composed, executed, and transformed.

12. Explain the difference between Add and Attach methods in Entity Framework.

The Add method is used to add new entities to the context, while the Attach method is used to attach existing entities to the context and mark them as unchanged.

13. What are the different types of relationships supported by Entity Framework?

Entity Framework supports three types of relationships: one-to-one, one-to-many, and many-to-many.

14. How can you define a one-to-one relationship in Entity Framework?

A one-to-one relationship in Entity Framework can be defined by adding a foreign key property to one of the entities and using the ForeignKey attribute to specify the relationship.

15. How can you define a one-to-many relationship in Entity Framework?

A one-to-many relationship in Entity Framework can be defined by adding a navigation property to the “one” side entity and a foreign key property to the “many” side entity.

16. How can you define a many-to-many relationship in Entity Framework?

A many-to-many relationship in Entity Framework can be defined by adding navigation properties to both entities and configuring a join table to store the relationship.

17. What is Database First approach in Entity Framework?

Database First is an approach in Entity Framework where the entity model is generated from an existing database by reverse engineering the database schema.

18. What is Model First approach in Entity Framework?

Model First is an approach in Entity Framework where the entity model is created visually using the Entity Designer and then the database schema is generated from the model.

19. What is the purpose of migrations in Entity Framework?

Migrations in Entity Framework enable developers to evolve the database schema over time by creating incremental changes to the model and applying them to the database.

20. What is the purpose of the Database.SqlQuery method in Entity Framework?

The Database.SqlQuery method in Entity Framework allows executing raw SQL queries and mapping the results to entity objects.

21. How can you enable logging in Entity Framework?

Logging in Entity Framework can be enabled by configuring the context to log SQL statements and other information using the Database.Log property.

22. What is the purpose of the Entity Framework Designer in Visual Studio?

The Entity Framework Designer in Visual Studio provides a visual interface for designing entity models and mapping the entities to the database schema.

23. How can you improve performance in Entity Framework?

Performance in Entity Framework can be improved by using techniques such as eager loading, disabling change tracking, using compiled queries, and optimizing database queries.

24. What is the purpose of the Database First Approach?

The Database First Approach allows you to create entity classes and a context class based on an existing database. It is useful when working with legacy databases or databases created by other tools.

25. How can you execute stored procedures in Entity Framework?

Stored procedures can be executed in Entity Framework using the DbContext.Database.SqlQuery or DbContext.Database.ExecuteSqlCommand methods.

These are just a few sample Entity Framework interview questions. Remember to prepare for the interview by understanding the fundamentals of Entity Framework and practicing coding scenarios.