ASP.NET Core Entity Framework Core 3

Question 1

What is the N+1 query problem in Entity Framework Core?

Accepted Answer

Executing one query to fetch a list then N additional queries for each item's related data

Answer

Running N parallel queries and one summary query

Answer

A naming issue with N-level deep relationships

Answer

Querying the same entity N+1 times by mistake

Question 2

Which EF Core method allows executing raw SQL and returning entity results?

Accepted Answer

FromSqlRaw()

Answer

ExecuteSqlRaw()

Answer

SqlQuery()

Answer

RunSql()

Question 3

What does the [Required] data annotation do on an EF Core entity property?

Accepted Answer

Marks the database column as NOT NULL and adds model validation

Answer

Makes the property the primary key

Answer

Creates a unique constraint on the column

Answer

Triggers a database-level constraint check

Question 4

Which EF Core feature automatically creates the database schema from the model without migrations?

Accepted Answer

EnsureCreated()

Answer

MigrateAsync()

Answer

AutoSchema()

Answer

CreateDatabase()

Question 5

How do you configure a one-to-many relationship in EF Core Fluent API?

Accepted Answer

HasMany().WithOne()

Answer

OneToMany().Configure()

Answer

AddRelationship().OneToMany()

Answer

MapRelation(1, '*')

Question 6

What is the purpose of value converters in Entity Framework Core?

Accepted Answer

To convert property values between CLR types and database types during reads and writes

Answer

To validate values before saving to the database

Answer

To convert between entity versions during migrations

Answer

To transform query results into DTOs