Top 120 Entity Framework Interview Questions and Answers PDF Download

Top 120 Entity Framework Interview Questions and Answers PDF Download

1. What is Entity Framework (EF)?

   • Entity Framework is an Object-Relational Mapping (ORM) framework that allows developers to work with relational databases using .NET objects.

2. Explain Code-First, Database-First, and Model-First approaches in Entity Framework.

   • Code-First: Developers define domain classes first, and the database is created based on these classes.
   • Database-First: Developers create the database first, and then the EF model is generated based on the database schema.
   • Model-First: Developers design the EF model using the Entity Data Model Designer, and the database schema is generated from the model.

3. What is the use of DbContext in Entity Framework?

   • DbContext is a class in EF that represents a session with the database and allows interaction with the database using DbSet<TEntity> properties.

4. Explain the difference between DbSet and IQueryable in Entity Framework.

   • DbSet: It represents a table in the database and allows CRUD operations.
   • IQueryable: It is used for defining queries against a data source. It allows composing queries without executing them immediately.

5. What is Database Migrations in Entity Framework?

   • Database Migrations is a feature in EF that allows developers to manage changes to the database schema over time.

6. What is the purpose of the DbMigrationsConfiguration class?

   • The DbMigrationsConfiguration class is used to configure database migrations settings, such as automatic migration and seed data.

7. What does the "AutomaticMigrationsEnabled" property do in DbMigrationsConfiguration class?

   • The "AutomaticMigrationsEnabled" property, when set to true, enables automatic migration in EF, meaning that database changes are applied automatically.

8. How do you enable automatic migrations in Entity Framework?

   • You can enable automatic migrations by setting the "AutomaticMigrationsEnabled" property to true in the DbMigrationsConfiguration class.

9. Explain Entity Framework Bulk Insert.

   • Entity Framework Bulk Insert is a technique to insert multiple records into a database table in a single database round-trip, which is faster than inserting records one by one.

10. What is Entity Framework Fluent API?

    • Fluent API is a set of configuration methods in EF that allows developers to define entity and relationship configurations using a fluent syntax instead of attributes.

11. How do you configure a one-to-many relationship using Fluent API in Entity Framework?

    • You can use the HasMany and WithOne methods to configure a one-to-many relationship between entities.

12. What is Pluralsight Entity Framework?

    • Pluralsight is an online learning platform that offers Entity Framework courses and tutorials to help developers enhance their skills.

13. How do you use Entity Framework with PostgreSQL (ef postgresql)?

    • To use Entity Framework with PostgreSQL, you need to install the Npgsql.EntityFrameworkCore.PostgreSQL NuGet package and configure the DbContext to use the Npgsql provider.

14. Who is Julie Lerman in the context of Entity Framework?

    • Julie Lerman is a well-known author and Microsoft MVP (Most Valuable Professional) who has written books and courses on Entity Framework.

15. How do you use Entity Framework with Oracle (Oracle EntityFrameworkCore)?

    • To use Entity Framework with Oracle, you need to install the Oracle.EntityFrameworkCore NuGet package and configure the DbContext to use the Oracle provider.

16. What is Entity Framework CosmosDB?

    • Entity Framework CosmosDB is a provider that allows developers to use EF with Azure Cosmos DB, a globally distributed NoSQL database service.

17. How do you use Entity Framework with MongoDB (EFCore MongoDB)?

    • To use Entity Framework with MongoDB, you need to install the MongoDB.EntityFrameworkCore NuGet package and configure the DbContext to use the MongoDB provider.

18. How does Entity Framework work with Blazor (Blazor Entity Framework)?

    • Blazor Entity Framework allows developers to use Entity Framework in Blazor web applications to interact with databases and perform CRUD operations.

19. How do you use Entity Framework with Blazor (Blazor EFCore)?

    • To use Entity Framework with Blazor, you need to add the Entity Framework Core NuGet package to your Blazor project and set up the DbContext as you would in any other .NET project.

20. How do you use Microsoft Entity Framework Core with SQL Server (Microsoft.EntityFrameworkCore.SqlServer)?

    • To use EF Core with SQL Server, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server provider.

21. Explain the purpose of Fluent API in Entity Framework?

    • Fluent API in Entity Framework allows developers to configure model classes and relationships with more flexibility and control than using attributes.

22. How do you specify the primary key using Fluent API in Entity Framework?

    • You can use the HasKey method in Fluent API to specify the primary key for an entity.

23. What is the .NET Framework Data Provider for MySQL (Visual Studio 2022)?

    • The .NET Framework Data Provider for MySQL is a data provider that allows .NET applications to communicate with MySQL databases.

24. How do you use Entity Framework Core with PostgreSQL (EFCore Postgres)?

    • To use EF Core with PostgreSQL, you need to install the Npgsql.EntityFrameworkCore.PostgreSQL NuGet package and configure the DbContext to use the Npgsql provider.

25. How do you use Entity Framework with MongoDB (Entity Framework MongoDB)?

• To use Entity Framework with MongoDB, you need to install the MongoDB.EntityFramework NuGet package and configure the DbContext to use the MongoDB provider.

26. Explain Database-First approach in Entity Framework.

    • Database-First approach in Entity Framework involves creating the database first, and then generating the EF model from the existing database schema.

27. What is the purpose of the Entity Framework Power Tools?

    • Entity Framework Power Tools is an extension that provides additional design-time features, such as viewing entity data, reverse engineering code from an existing database, and generating views for complex types.

28. What is the purpose of eager loading in Entity Framework?

    • Eager loading in Entity Framework is a technique to load related entities along with the main entity in a single query to reduce the number of database round-trips.

29. What is lazy loading in Entity Framework?

    • Lazy loading in Entity Framework is a feature that loads related entities from the database only when they are accessed for the first time, reducing the initial loading time.

30. How do you enable lazy loading in Entity Framework?

    • Lazy loading is enabled by default in Entity Framework. To disable it, you can use the LazyLoadingEnabled property in the DbContext and set it to false.

31. Explain the concept of self-tracking entities in Entity Framework.

    • Self-tracking entities in Entity Framework are entities that can automatically detect changes made to their properties and persist those changes back to the database.

32. What are the differences between Entity Framework and Entity Framework Core?

    • Entity Framework is part of the .NET Framework and is fully featured, while Entity Framework Core is a cross-platform, lightweight version of EF with some feature limitations.

33. How do you enable explicit loading in Entity Framework?

    • Explicit loading in Entity Framework can be done using the DbEntityEntry class and the Collection or Reference method to load related entities explicitly.

34. Explain the purpose of the "Database First" approach in Entity Framework Core.

    • The "Database First" approach in Entity Framework Core involves creating a DbContext and entity classes based on an existing database schema using scaffolding or reverse engineering.

35. What is the role of the SaveChanges method in Entity Framework?

    • The SaveChanges method in Entity Framework is used to persist changes made to entities in the context back to the database.

36. How do you perform explicit transaction management in Entity Framework?

    • You can use the Database.BeginTransaction method to explicitly begin a transaction, and then use the SaveChanges method to commit or rollback the transaction based on the outcome.

37. Explain the OnModelCreating method in Entity Framework.

    • The OnModelCreating method is overridden in the DbContext class and is used to configure the model using Fluent API.

38. What is the purpose of the Required attribute in Entity Framework?

    • The Required attribute is used to specify that a property in an entity must have a non-null value when saving changes to the database.

39. Explain the StringLength attribute in Entity Framework.

    • The StringLength attribute is used to specify the maximum length of a string property in an entity.

40. How do you use Entity Framework Core with SQLite (EFCore SQLite)?

    • To use EF Core with SQLite, you need to install the Microsoft.EntityFrameworkCore.Sqlite NuGet package and configure the DbContext to use the SQLite provider.

41. What is an entity key in Entity Framework?

    • An entity key in Entity Framework is a unique identifier that uniquely identifies an entity instance in the context.

42. How do you use Entity Framework Core with MySQL (EFCore MySQL)?

    • To use EF Core with MySQL, you need to install the MySql.EntityFrameworkCore NuGet package and configure the DbContext to use the MySQL provider.

43. Explain the purpose of the ConcurrencyCheck attribute in Entity Framework.

    • The ConcurrencyCheck attribute is used to specify that a property should be included in optimistic concurrency checks.

44. What is the role of the DbSet class in Entity Framework?

    • The DbSet class in Entity Framework represents a collection of entities of a specific type and allows querying and managing entities in the context.

45. How do you use Entity Framework Core with SQL Server Compact Edition (EFCore SQL CE)?

    • To use EF Core with SQL Server Compact Edition, you need to install the Microsoft.EntityFrameworkCore.SqlServerCompact NuGet package and configure the DbContext to use the SQL CE provider.

46. Explain the purpose of the InverseProperty attribute in Entity Framework.

    • The InverseProperty attribute is used to specify the navigation property that represents the other end of a one-to-many or many-to-many relationship.

47. What are stored procedures in Entity Framework, and how do you use them?

    • Stored procedures in Entity Framework are precompiled database objects that can be used to perform specific database operations. You can use the DbSet.FromSql method to call stored procedures from EF.

48. What is the purpose of the Timestamp attribute in Entity Framework?

    • The Timestamp attribute is used to specify that a property should be included in optimistic concurrency checks as a row version.

49. Explain the role of the Include method in Entity Framework.

    • The Include method in Entity Framework is used to specify the related entities that should be included in the query result when using eager loading.

50. How do you use Entity Framework Core with Oracle (EFCore Oracle)?

• To use EF Core with Oracle, you need to install the Oracle.EntityFrameworkCore NuGet package and configure the DbContext to use the Oracle provider.

51. What is the purpose of the NotMapped attribute in Entity Framework?

    • The NotMapped attribute is used to specify that a property should not be mapped to a column in the database and is excluded from database operations.

52. Explain the concept of database seeding in Entity Framework.

    • Database seeding in Entity Framework is the process of populating the database with initial data during the database creation or migration.

53. What is the purpose of the Key attribute in Entity Framework?

    • The Key attribute is used to specify that a property should be used as a primary key in the database.

54. Explain the Database.SetInitializer method in Entity Framework.

    • The Database.SetInitializer method is used to set the database initializer that specifies how the database should be created and initialized.

55. What is the role of the Navigation Property in Entity Framework?

    • Navigation properties in Entity Framework are used to represent relationships between entities and enable navigation between related entities.

56. How do you enable lazy loading in Entity Framework Core (EF Core)?

    • In Entity Framework Core, lazy loading is not enabled by default. You can enable it by installing the Microsoft.EntityFrameworkCore.Proxies NuGet package and configuring the DbContext to use proxy classes.

57. Explain the purpose of the MaxLength attribute in Entity Framework.

    • The MaxLength attribute is used to specify the maximum length of a string or binary property in an entity.

58. What is the role of the Required method in Entity Framework Core (EF Core)?

    • In Entity Framework Core, the Required method is used to specify that a property is required and must have a non-null value in the database.

59. Explain the concept of migrations in Entity Framework Core (EF Core).

    • Migrations in EF Core are used to manage changes to the database schema over time. They allow developers to update the database to a new version as the application evolves.

60. How do you add a new migration in Entity Framework Core (EF Core)?

    • To add a new migration in EF Core, you can use the Add-Migration command in the Package Manager Console (PMC) or the dotnet ef migrations add command in the terminal.

61. What is the purpose of the ConcurrencyStamp property in Entity Framework Core (EF Core)?

    • The ConcurrencyStamp property is used for optimistic concurrency control in EF Core. It helps to detect and prevent concurrent updates to the same entity.

62. How do you configure the connection string in Entity Framework Core (EF Core)?

    • The connection string in EF Core is typically configured in the DbContext class using the OnConfiguring method or through dependency injection in the Startup class.

63. Explain the Ignore method in Entity Framework Core (EF Core).

    • The Ignore method in EF Core is used to specify that a property should be ignored and not mapped to a column in the database.

64. What is the purpose of the ConcurrencyCheck method in Entity Framework Core (EF Core)?

    • The ConcurrencyCheck method in EF Core is used to specify that a property should be included in optimistic concurrency checks.

65. Explain the HasDefaultValue method in Entity Framework Core (EF Core).

    • The HasDefaultValue method in EF Core is used to specify a default value for a property in the database when inserting new entities.

66. What is the role of the DbSet.Find method in Entity Framework Core (EF Core)?

    • The DbSet.Find method is used to find an entity with the given primary key values in the context without making a database query.

67. How do you use Entity Framework Core with SQL Server Express LocalDB (EF Core SQL Server Express LocalDB)?

    • To use EF Core with SQL Server Express LocalDB, you need to install the Microsoft.EntityFrameworkCore.SqlServer and Microsoft.EntityFrameworkCore.SqlServer.LocalDb NuGet packages, and configure the DbContext to use the SQL Server LocalDB provider.

68. Explain the HasOne method in Entity Framework Core (EF Core).

    • The HasOne method in EF Core is used to configure a one-to-one relationship between entities.

69. What is the purpose of the Find method in Entity Framework?

    • The Find method in Entity Framework is used to find an entity with the given primary key values in the context. It queries the database if the entity is not already loaded.

70. How do you use Entity Framework Core with SQLite in-memory database (EF Core SQLite in-memory)?

    • To use EF Core with SQLite in-memory database, you need to install the Microsoft.EntityFrameworkCore.Sqlite NuGet package and configure the DbContext to use the SQLite provider with an in-memory database connection.

71. Explain the HasColumnType method in Entity Framework.

    • The HasColumnType method in Entity Framework is used to specify the database column data type for a property.

72. What is the purpose of the Computed attribute in Entity Framework?

    • The Computed attribute is used to specify that a property in an entity is computed and not mapped to a database column.

73. How do you use Entity Framework Core with SQL Server Azure (EF Core SQL Server Azure)?

    • To use EF Core with SQL Server Azure, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server Azure provider.

74. Explain the concept of database-first migration in Entity Framework Core (EF Core).

    • Database-first migration in EF Core involves creating the database first, and then generating the EF Core model from the existing database schema using scaffolding or reverse engineering.

75. What is the purpose of the HasDiscriminator method in Entity Framework Core (EF Core)?

    • The HasDiscriminator method in EF Core is used to configure a discriminator column for inheritance mapping in table-per-hierarchy (TPH) inheritance.

76. How do you use Entity Framework Core with SQL Server LocalDB (EF Core SQL Server LocalDB)?

    • To use EF Core with SQL Server LocalDB, you need to install the Microsoft.EntityFrameworkCore.SqlServer and Microsoft.EntityFrameworkCore.SqlServer.LocalDb NuGet packages, and configure the DbContext to use the SQL Server LocalDB provider.

77. Explain the HasMany method in Entity Framework Core (EF Core).

    • The HasMany method in EF Core is used to configure a one-to-many relationship between entities.

78. What is the purpose of the Column attribute in Entity Framework?

    • The Column attribute is used to specify the database column name for a property in an entity.

79. How do you use Entity Framework Core with SQL Server (EF Core SQL Server)?

    • To use EF Core with SQL Server, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server provider.

80. Explain the concept of table-per-hierarchy (TPH) inheritance in Entity Framework.

    • Table-per-hierarchy (TPH) inheritance in Entity Framework is a strategy where all classes in an inheritance hierarchy are mapped to a single database table.

81. What is the purpose of the Discriminator column in Entity Framework Core (EF Core)?

    • The Discriminator column in EF Core is used to store the discriminator value that determines the type of entity in table-per-hierarchy (TPH) inheritance.

82. How do you use Entity Framework Core with SQL Server Compact Edition (EF Core SQL CE)?

    • To use EF Core with SQL Server Compact Edition, you need to install the Microsoft.EntityFrameworkCore.SqlServerCompact NuGet package and configure the DbContext to use the SQL CE provider.

83. Explain the HasAlternateKey method in Entity Framework Core (EF Core).

    • The HasAlternateKey method in EF Core is used to specify an alternate key for an entity.

84. What is the purpose of the ConcurrencyMode property in Entity Framework?

    • The ConcurrencyMode property in Entity Framework is used to specify the concurrency mode for a property in optimistic concurrency control.

85. How do you use Entity Framework Core with PostgreSQL (EF Core PostgreSQL)?

    • To use EF Core with PostgreSQL, you need to install the Npgsql.EntityFrameworkCore.PostgreSQL NuGet package and configure the DbContext to use the Npgsql provider.

86. Explain the concept of table-per-type (TPT) inheritance in Entity Framework.

    • Table-per-type (TPT) inheritance in Entity Framework is a strategy where each class in an inheritance hierarchy is mapped to its own database table.

87. What is the purpose of the ColumnOrder property in Entity Framework?

    • The ColumnOrder property in Entity Framework is used to specify the order of columns in the database table for an entity.

88. How do you use Entity Framework Core with SQLite (EF Core SQLite)?

    • To use EF Core with SQLite, you need to install the Microsoft.EntityFrameworkCore.Sqlite NuGet package and configure the DbContext to use the SQLite provider.

89. Explain the HasIndex method in Entity Framework Core (EF Core).

    • The HasIndex method in EF Core is used to configure an index for one or more properties in an entity to improve query performance.

90. What is the purpose of the DefaultValue attribute in Entity Framework?

    • The DefaultValue attribute is used to specify a default value for a property in an entity in the database.

91. How do you use Entity Framework Core with MySQL (EF Core MySQL)?

    • To use EF Core with MySQL, you need to install the MySql.EntityFrameworkCore NuGet package and configure the DbContext to use the MySQL provider.

92. Explain the concept of table-per-concrete-type (TPC) inheritance in Entity Framework.

    • Table-per-concrete-type (TPC) inheritance in Entity Framework is a strategy where each class in an inheritance hierarchy is mapped to its own database table without sharing columns with other classes.

93. What is the purpose of the DatabaseGenerated attribute in Entity Framework?

    • The DatabaseGenerated attribute is used to specify how the database generates values for a property, such as an identity column.

94. How do you use Entity Framework Core with SQL Server (EF Core SQL Server) in a .NET Core project?

    • To use EF Core with SQL Server in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server provider.

95. Explain the concept of table-splitting in Entity Framework.

    • Table-splitting in Entity Framework is a technique where a single entity is split into multiple database tables.

96. What is the purpose of the NotMapped method in Entity Framework Core (EF Core)?

    • The NotMapped method in EF Core is used to specify that a property should not be mapped to a column in the database.

97. How do you use Entity Framework Core with SQL Server Compact Edition (EF Core SQL CE) in a .NET Core project?

    • To use EF Core with SQL Server Compact Edition in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServerCompact NuGet package and configure the DbContext to use the SQL CE provider.

98. Explain the AsNoTracking method in Entity Framework Core (EF Core).

    • The AsNoTracking method in EF Core is used to query entities without tracking their changes, resulting in improved query performance.

99. What is the purpose of the DefaultValueSql method in Entity Framework Core (EF Core)?

    • The DefaultValueSql method in EF Core is used to specify a SQL expression that provides a default value for a property in the database.

100. How do you use Entity Framework Core with SQL Server Azure (EF Core SQL Server Azure) in a .NET Core project?

• To use EF Core with SQL Server Azure in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server Azure provider.

101. Explain the purpose of the CompositeKey attribute in Entity Framework.

     • The CompositeKey attribute is used to specify multiple properties as part of a composite key in an entity.

102. How do you use Entity Framework Core with SQLite in-memory database (EF Core SQLite in-memory) in a .NET Core project?

     • To use EF Core with SQLite in-memory database in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.Sqlite NuGet package and configure the DbContext to use the SQLite provider with an in-memory database connection.

103. Explain the concept of table-per-type (TPT) inheritance in Entity Framework Core (EF Core).

     • Table-per-type (TPT) inheritance in EF Core is a strategy where each class in an inheritance hierarchy is mapped to its own database table, and the shared properties are stored in the base table.

104. What is the purpose of the ConcurrencyMode attribute in Entity Framework?

     • The ConcurrencyMode attribute is used to specify the concurrency mode for a property in optimistic concurrency control.

105. How do you use Entity Framework Core with PostgreSQL (EF Core PostgreSQL) in a .NET Core project?

     • To use EF Core with PostgreSQL in a .NET Core project, you need to install the Npgsql.EntityFrameworkCore.PostgreSQL NuGet package and configure the DbContext to use the Npgsql provider.

106. Explain the UseQuerySplittingBehavior method in Entity Framework Core (EF Core).

     • The UseQuerySplittingBehavior method in EF Core is used to specify how EF Core should handle queries that involve filtered includes.

107. What is the purpose of the InverseProperty attribute in Entity Framework Core (EF Core)?

     • The InverseProperty attribute is used to specify the navigation property that represents the other end of a one-to-many or many-to-many relationship.

108. How do you use Entity Framework Core with SQL Server LocalDB (EF Core SQL Server LocalDB) in a .NET Core project?

     • To use EF Core with SQL Server LocalDB in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServer and Microsoft.EntityFrameworkCore.SqlServer.LocalDb NuGet packages, and configure the DbContext to use the SQL Server LocalDB provider.

109. Explain the concept of table-per-concrete-type (TPC) inheritance in Entity Framework Core (EF Core).

     • Table-per-concrete-type (TPC) inheritance in EF Core is a strategy where each class in an inheritance hierarchy is mapped to its own database table without sharing columns with other classes.

110. What is the purpose of the Computed method in Entity Framework Core (EF Core)?

     • The Computed method in EF Core is used to specify that a property in an entity is computed and not mapped to a database column.

111. How do you use Entity Framework Core with SQL Server Azure (EF Core SQL Server Azure) in a .NET Core project?

     • To use EF Core with SQL Server Azure in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServer NuGet package and configure the DbContext to use the SQL Server Azure provider.

112. Explain the UseLazyLoadingProxies method in Entity Framework Core (EF Core).

     • The UseLazyLoadingProxies method in EF Core is used to enable lazy loading of navigation properties by creating proxy classes.

113. What is the purpose of the HasDatabaseGeneratedOption method in Entity Framework?

     • The HasDatabaseGeneratedOption method is used to specify how the database generates values for a property, such as an identity column.

114. How do you use Entity Framework Core with SQL Server Compact Edition (EF Core SQL CE) in a .NET Core project?

     • To use EF Core with SQL Server Compact Edition in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.SqlServerCompact NuGet package and configure the DbContext to use the SQL CE provider.

115. Explain the concept of table-splitting in Entity Framework Core (EF Core).

     • Table-splitting in EF Core is a technique where a single entity is split into multiple database tables.

116. What is the purpose of the ToTable method in Entity Framework Core (EF Core)?

     • The ToTable method in EF Core is used to specify the name of the database table associated with an entity.

117. How do you use Entity Framework Core with SQLite (EF Core SQLite) in a .NET Core project?

     • To use EF Core with SQLite in a .NET Core project, you need to install the Microsoft.EntityFrameworkCore.Sqlite NuGet package and configure the DbContext to use the SQLite provider.

118. Explain the HasData method in Entity Framework Core (EF Core).

     • The HasData method in EF Core is used to seed the database with initial data during migration or database creation.

119. What is the purpose of the DatabaseGeneratedOption attribute in Entity Framework?

     • The DatabaseGeneratedOption attribute is used to specify how the database generates values for a property, such as an identity column.

120. How do you use Entity Framework Core with MySQL (EF Core MySQL) in a .NET Core project?

• To use EF Core with MySQL in a .NET Core project, you need to install the MySql.EntityFrameworkCore NuGet package and configure the DbContext to use the MySQL provider.

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