60+ Entity Framework interview questions to hire top developers

If your development team relies on Entity Framework for data management in .NET applications, finding the right talent is key.

To help you find and hire the best candidates who know Entity Framework (EF) inside out, we've put together a list of more than 60 Entity Framework interview questions. To make the candidate evaluation process easier for you, even if you’re not an EF expert, we’ve also included sample answers to 20 of them. 

These questions will help you assess the technical proficiency and hands-on experience of your candidates, ensuring they have the skills you need. Combine them with behavioral questions for a more in-depth evaluation of your candidates.

But before you move on to interviews, there’s a more pressing question you need to know the answer to: How do you filter candidates and decide whom to interview?

Use pre-employment skills testing to screen applicants and assess their real skills. Use our .NET test or our Database Management and Administration test to create a thorough evaluation process. 

This approach will enable you to filter out unqualified candidates and zero in on those who truly have the skills your team needs. 

Top 20 Entity Framework interview questions and answers to hire the best

In this section, we’ve selected the best 20 interview questions you can ask applicants to assess their proficiency in Entity Framework. You’ll also find sample answers to help you evaluate candidates’ responses. 

1. Explain the differences between Code First, Database First, and Model First approaches in EF.

The best candidates will be able to explain the differences in detail. Here are key elements to look for:

• Code First: This approach starts with writing C# or VB.NET classes, which represent your data model. Entity Framework then generates the database schema based on these classes. Code First is ideal for new projects which don't have a database schema yet. It offers the flexibility to define your data structure using code and let EF handle the database creation and updates.

• Database First: In this approach, developers begin with an existing database. Entity Framework generates the data model classes based on the current schema. Database First is perfect for projects involving legacy databases or cases where the database design is managed separately from the application code.

• Model First: With Model First, developers use a visual designer to create your data model. EF then generates both the classes and the database schema from it. This approach is useful if developers want to visually plan and modify the database schema before generating the actual code and database.

2. What are the main advantages of using Entity Framework in a .NET application?

Entity Framework saves development time by reducing the amount of boilerplate code needed for data access. This enables developers to focus on the business logic rather than writing repetitive SQL queries. 

It also enhances maintainability and makes the code easier to read, update, and debug. Plus, it provides an intuitive way to interact with the database, enabling developers to manipulate data using familiar .NET objects and methods.

Use a .NET test to evaluate candidates’ knowledge of this framework in depth.

3. How does Entity Framework handle object-relational mapping?

Entity Framework maps .NET objects to database tables and uses configurations and conventions to align classes and properties with database tables and columns. For example, a class in the code maps to a table in the database, and its properties map to the table's columns. 

EF also supports relationships between objects, like one-to-many or many-to-many, translating these into appropriate database schema elements. This mapping ensures developers can work with data in an object-oriented way while EF manages the underlying database interactions.

4. What is DbContext and how is it used in EF?

DbContext serves as the central hub for all database operations in EF, simplifying the management and organization of your data access code. It manages the database connection and handles querying and saving data and acts as a bridge between your domain classes and the database. 

Developers can use DbContext to interact with the database through methods like SaveChanges for saving data and LINQ queries for retrieving data. 

5. How does Entity Framework support lazy loading? What are its pros and cons?

Entity Framework supports lazy loading by delaying the loading of related data until it's needed. When the user first accesses a navigation property, EF retrieves the related data from the database. This reduces initial load time and memory usage by loading only necessary data on demand. 

However, lazy loading can lead to performance issues, like the N+1 query problem, where multiple small queries are sent to the database, causing delays. Because of this, developers need lazy loading judiciously and be aware of its impact on performance.

6. What is eager loading? When would you use it?

Eager loading in Entity Framework loads related data along with the main data in a single query, using the Include method. Developers can use eager loading when they know they’ll need related data upfront and want to avoid the performance overhead of multiple queries. 

By loading all necessary data at once, they can improve the efficiency of data access operations. 

7. What’s the purpose of the OnModelCreating method?

The OnModelCreating method configures models that EF creates from domain classes. Software engineers can override this method in the DbContext class to use the Fluent API and specify configurations like table mappings, relationships, and constraints. 

They can configure primary keys, foreign keys, table names, or set up complex mappings that aren’t possible with data annotations alone. 

8. How does Entity Framework handle database migrations?

Knowledgeable candidates will know that Entity Framework manages migrations by tracking changes to the data model and applying these changes to the database schema. 

Developers can use commands like Add-Migration to create migration files that describe the changes, and Update-Database to apply these changes to the database. This process helps keep the database schema in sync with the code.

9. What’s the purpose of the Fluent API in EF?

The Fluent API in Entity Framework enables developers to configure the model using method chaining, offering more control over the configuration than data annotations. 

Expect candidates to mention that with it, they can define mappings, relationships, and constraints that can't be expressed through attributes alone, providing a flexible way to set up your data model.

10. How do you implement a many-to-many relationship in EF Core?

In EF Core, developers can create a many-to-many relationship by defining a join entity class that represents the relationship. This class contains foreign keys pointing to the related entities. 

They can configure the relationship using the Fluent API in the OnModelCreating method, specifying the composite keys and navigation properties for the join entity.

11. How would you handle a situation where EF generates inefficient SQL queries?

Top candidates will explain that to handle inefficient SQL queries generated by EF, they’d: 

• Start by profiling the queries to identify performance bottlenecks

• Optimize the LINQ queries or use raw SQL for complex scenarios

• Refactor the data model if necessary

• Use eager loading to reduce the number of queries

Additionally, they might consider indexing database tables to improve query performance.

12. How do you handle complex queries that are difficult to express with LINQ in EF?

For those queries, developers can use raw SQL queries with the FromSqlRaw method. This approach helps ensure complex joins and subqueries are handled efficiently while still benefiting from EF’s change tracking and materialization. 

Additionally, they could use stored procedures by defining them in the database and calling them from EF. Stored procedures encapsulate complex logic, improve performance, and centralize queries within the database. 

13. Describe how you would approach adding EF to an existing database-first project.

Here, applicants should explain that they would:

• Start by reverse-engineering the database schema using the Scaffold-DbContext command

• Configure the DbContext and update the generated classes as needed

• Integrate Entity Framework into your project by replacing direct database calls with EF queries and operations

• Test thoroughly to maintain data integrity and performance

14. What are the performance implications of using Entity Framework compared to direct SQL queries?

Entity Framework can be slower than direct SQL queries because it adds an abstraction layer, translating LINQ queries into SQL. 

This can lead to less optimized queries and additional overhead. To mitigate this, developers can optimize LINQ queries, use eager loading, and profile the generated SQL. For critical paths, they should consider using raw SQL queries.

15. How does Entity Framework handle circular references between entities?

Entity Framework handles circular references using navigation properties and foreign keys, establishing relationships between entities. Its change tracking mechanism navigates these circular references efficiently, ensuring the correct tracking and updating of related entities. 

However, when serializing entities with circular references, software engineers need to handle them carefully to avoid infinite loops. Often, they use attributes like [JsonIgnore] to exclude navigation properties from serialization. 

Alternatively, they can use DTOs (Data Transfer Objects) to flatten the structure, ensuring that they only serialize the necessary data, which helps prevent issues with circular references.

16. How do you customize conventions in EF Core?

Candidates should explain that to customize conventions in EF Core, they can use the Fluent API in the OnModelCreating method. This overrides default conventions by specifying custom configurations for table names, column types, relationships, and constraints. 

17. How do you ensure the quality and maintainability of EF code in your projects?

Expect candidates to mention some of the following best practices for clean code in Entity Framework: 

• Use strongly-typed queries

• Avoid magic strings

• Keep the DbContext scope manageable

• Regularly refactor code to improve readability

• Write unit tests for data access logic

• Document complex configurations

Consistent code reviews and adherence to coding standards also help.

18. What are some common challenges when using EF, and how do you handle them?

Skilled candidates will explain some of the following common issues and how they handle them: 

• Performance issues: Optimize queries and use raw SQL when needed

• Complex queries: Use stored procedures or raw SQL

• Conflicts and schema updates: Manage migrations carefully, especially in a team environment

19. What are the differences between EF 6 and EF Core?

Expect candidates to explain that EF 6 is a mature, feature-rich object-relational mapper (ORM) for .NET Framework, while EF Core is a lightweight, cross-platform version designed for .NET Core. 

EF Core offers better performance, supports multiple database providers, and has a more modular design, but it lacks some features of EF 6.

20. How does EF Core handle asynchronous database operations?

EF Core supports asynchronous database operations using async methods like SaveChangesAsync and ToListAsync. These methods help improve application responsiveness and scalability by freeing up threads while waiting for database operations to complete. 

42 additional interview questions you can ask to assess Entity Framework knowledge

If you need more question ideas, below you’ll find 42 extra Entity Framework interview questions you can ask candidates. 

1. Explain the role of DbSet in Entity Framework.

2. What is the difference between Add() and Attach() methods in EF?

3. How does Entity Framework handle concurrency conflicts?

4. What is the role of the DbChangeTracker in EF?

5. Explain the concept of shadow properties in EF Core.

6. How does EF Core handle value conversions?

7. What are navigation properties in EF?

8. How does EF manage relationships between entities?

9. What is the difference between a one-to-many and a many-to-many relationship in EF?

10. How do you configure a composite key in EF?

11. How would you handle database migrations in EF Core?

12. Show how to use the Include method to perform eager loading in EF.

13. How do you configure cascade delete in EF?

14. How do you seed initial data in an EF Core application?

15. Show how to update an entity's properties without loading it from the database in EF.

16. How do you handle stored procedures?

17. Tell us about a situation where you optimized an EF query for better performance.

18. How would you implement soft deletes in EF Core?

19. Describe a time when you had to troubleshoot a complex issue with EF migrations.

20. How would you update a legacy application to use EF?

21. How would you handle dynamic query generation based on user input?

22. Explain how you manage database transactions in EF.

23. Describe how you would use Entity Framework to implement a repository pattern.

24. Explain the purpose of the AsSplitQuery method in EF Core.

25. How do you use global query filters in EF Core?

26. Describe the purpose of the DbFunctions class in EF Core.

27. How do you implement auditing (e.g., tracking changes) in EF Core?

28. How does EF Core support database views?

29. What are some strategies for improving the performance of EF Core queries?

30. How does EF Core handle multi-tenancy?

31. Tell us about a time when you had to refactor EF code to improve performance or maintainability.

32. Describe a situation where you had to troubleshoot an EF-related issue under tight deadlines.

33. How do you prioritize features and bug fixes related to EF in a project?

34. Explain how you balance the use of Entity Framework with raw SQL queries in your applications.

35. How do you handle EF migrations in a CI/CD pipeline?

36. How does EF Core support different database providers?

37. Explain the role of the ModelBuilder class in EF Core.

38. How do you handle mapping complex types (value objects) in EF Core?

39. How do you implement custom conventions in EF Core?

40. Explain how you would configure EF Core to use a specific database schema.

41. How do you handle batch updates in EF Core?

42. What are some best practices for using Entity Framework in a high-performance application?

Check out our .NET interview questions for more inspiration.

Hire experts who are proficient in Entity Framework with skills tests and interview questions

To hire developers and software engineers who know how to make the most out of Entity Framework, you need to assess their abilities accurately and without bias. 

So, how can you do that? 

With skills testing and the right Entity Framework interview questions. To zero in on the best talent in your talent pool, build a skills assessment using our .NET, Database Management, and Clean Code tests – or check out our test library for more ideas. 

Then, invite top candidates to an interview and ask them some of the questions from this article to find the perfect match for your team. 

Sign up for a free 40-minute live demo to speak with one of our experts and see how to make the most out of TestGorilla – or try out our Free forever plan to build your first assessment today.