1. What is Entity Framework?
Entity Framework is an object-relational mapping (ORM) framework provided by Microsoft. It enables developers to work with relational data using domain-specific objects.

2. What are the different versions of Entity Framework?
The different versions of Entity Framework are EF 1, EF 4, EF 5, EF 6, and EF Core.

3. What is DbContext in Entity Framework?
DbContext is a class that is the primary entry point for accessing a database using Entity Framework. It represents a session with the database and provides several methods for querying, inserting, updating, and deleting entities.

4. What is a DbSet?
DbSet is a class in Entity Framework that represents a collection of entities from a particular table or view in the database. It allows CRUD operations on entities of a specific type.

5. What is Code First approach in Entity Framework?
Code First is an approach in Entity Framework where you define your domain model classes and Entity Framework generates the database schema based on those classes. It allows you to focus on the domain model and the code, rather than designing the database schema upfront.

6. What is Database First approach in Entity Framework?
Database First is an approach in Entity Framework where you create your database schema first, and then Entity Framework generates the corresponding domain model classes from the database schema.

7. What is Model First approach in Entity Framework?
Model First is an approach in Entity Framework where you design your domain model using the Entity Framework Designer or EdmGen tool, and then Entity Framework generates the database schema from the model.

8. What is lazy loading in Entity Framework?
Lazy loading is a feature in Entity Framework where related entities are loaded from the database only when accessed for the first time. This can improve performance by reducing the amount of data loaded initially.

9. What is eager loading in Entity Framework?
Eager loading is a feature in Entity Framework where related entities are loaded from the database along with the main entity, instead of loading them separately when accessed. This can improve performance by reducing the number of database round trips.

10. What is explicit loading in Entity Framework?
Explicit loading is a feature in Entity Framework where you can selectively load related entities on demand, using the Load method of the DbSet or the Entry object.

11. What is a navigation property in Entity Framework?
A navigation property in Entity Framework is a property in an entity class that represents a relationship between entities. It allows you to navigate from one entity to another through the relationship.

12. How do you define relationships between entities in Entity Framework?
You can define relationships between entities in Entity Framework using navigation properties and foreign keys. Navigation properties represent the relationship, and foreign keys define the constraints between the related tables in the database.

13. What is the purpose of the Fluent API in Entity Framework?
The Fluent API in Entity Framework allows you to configure the database mapping and relationships between entities using a fluent interface, instead of relying on conventions or annotations.

14. What are migrations in Entity Framework?
Migrations in Entity Framework are a way to manage changes to your database schema over time. They allow you to update the database schema to match the changes in your domain model, without losing existing data.

15. What is the purpose of DbSet.Local property in Entity Framework?
The DbSet.Local property in Entity Framework returns an ObservableCollection of the entities that are currently being tracked by the DbContext. It can be used to access or manipulate the entities in memory without hitting the database.

16. What is the purpose of the Include method in Entity Framework?
The Include method in Entity Framework is used to specify related entities to be included in the query results. It allows you to load related entities along with the main entity, using eager loading.

17. How do you enable and disable change tracking in Entity Framework?
You can enable and disable change tracking in Entity Framework using the DbSet’s methods Add, Remove, Attach, and Detach. These methods control whether the context will track changes made to entities.

18. What is a repository pattern in Entity Framework?
The repository pattern is a software design pattern that allows you to decouple the data access layer from the business logic layer. It provides a way to query and manipulate entities using a consistent and abstract interface.

19. What is a unit of work in Entity Framework?
A unit of work in Entity Framework is a design pattern that defines a boundary for a set of related database operations. It allows you to group multiple operations into a single transaction and ensures consistency and atomicity.

20. How do you enable lazy loading and proxy creation in Entity Framework?
Lazy loading and proxy creation can be enabled in Entity Framework by marking the navigation properties as virtual in the entity classes and setting the LazyLoadingEnabled and ProxyCreationEnabled properties of the DbContext to true.

1. What is Entity Framework?
Entity Framework is an Object Relational Mapping (ORM) framework that enables developers to work with relational data using domain-specific objects.

2. What are the different components of Entity Framework?
The main components of Entity Framework are:
– Entity Data Model
– Entity Data Provider
– Object Services
– LINQ to Entities
– Entity SQL

3. What is the difference between Entity Framework and ADO.NET?
ADO.NET is a lower-level data access technology that provides more control over the data access process, while Entity Framework is an ORM that abstracts away the database specific details and allows developers to work with domain-specific objects.

4. What is the role of DbContext class in Entity Framework?
DbContext is the main class responsible for interacting with the database in Entity Framework. It represents a session with the database and allows CRUD operations using DbSet properties.

5. What is lazy loading in Entity Framework?
Lazy loading is a feature of Entity Framework that defers the loading of related entities until they are explicitly accessed. It improves performance by only loading the required data when needed.

6. What is eager loading in Entity Framework?
Eager loading is the opposite of lazy loading. It ensures that all the required related entities are loaded along with the main entity in a single database query. It can improve performance by minimizing database calls.

7. Explain the concept of code-first in Entity Framework.
Code-first is a development approach in Entity Framework where the database is created based on the model classes and their relationships defined in code. It allows developers to focus on the domain model rather than the database structure.

8. What is the difference between Database First and Model First approaches in Entity Framework?
In Database First approach, the database is already created and Entity Framework generates the model classes and mappings based on the existing database schema. In Model First approach, the model diagram is created first and then the database schema and classes are generated based on the model.

9. What is a migration in Entity Framework?
Migrations are a way to manage changes to the database schema over time. It allows easy deployment of database changes without losing data.

10. How can you improve Entity Framework performance?
Some ways to improve Entity Framework performance are:
– Use eager loading to minimize database calls
– Use compiled LINQ queries instead of dynamically generated ones
– Use caching for frequently accessed data
– Avoid unnecessary tracking of entities

11. What are complex types in Entity Framework?
Complex types are non-entity types in Entity Framework that represent structured data. They can be used as properties of an entity and are stored inline with the entity in the database.

12. What is the purpose of the Include() method in Entity Framework?
The Include() method is used to specify related entities to be included in the query result. It allows eager loading of specific navigation properties to retrieve the required data in a single database call.

13. How can you handle concurrency in Entity Framework?
Concurrency can be handled in Entity Framework by using optimistic concurrency. It can be achieved by including a timestamp column in the entity and checking its value during update operations to detect concurrent modifications.

14. What is the purpose of the Database First approach in Entity Framework?
The Database First approach is used when an existing database schema is already available. Entity Framework generates the model classes and mappings based on the database schema, allowing easy integration with the existing database.

15. What are the different types of associations in Entity Framework?
The different types of associations in Entity Framework are:
– One-to-One
– One-to-Many
– Many-to-Many

16. What is the purpose of Entity Framework Code First Migrations?
Code First Migrations allow the database schema to be automatically updated as the model changes. It handles changes such as adding or modifying tables, columns, relationships, etc., without losing data.

17. How can you execute raw SQL queries in Entity Framework?
In Entity Framework, raw SQL queries can be executed using the SqlQuery() method or by using the ExecuteSqlCommand() method. These methods provide a way to execute custom SQL queries and retrieve the results.

18. Explain Entity Framework transactions.
Entity Framework transactions allow multiple operations to be grouped together as a single unit of work. Transactions ensure that all the operations either complete successfully or fail as a whole.

19. What are the different transaction isolation levels supported by Entity Framework?
Entity Framework supports the following transaction isolation levels:
– Read Uncommitted
– Read Committed
– Repeatable Read
– Serializable
– Snapshot

20. What is the purpose of the AsNoTracking() method in Entity Framework?
The AsNoTracking() method in Entity Framework disables entity tracking, allowing read-only operations to perform faster by skipping the overhead of tracking changes to the entities.