Introduction to Entity Framework

Question 1

What is Object-Relational-Mapping?

Answer 1

The idea of being able to write queries like
this, as well as much more complicated ones, using your preferred object-oriented programming language

Question 2

What are the advantages of using ORM?

Answer 2

• Language Fluency
• Abstracts Database Systems
• Advanced Features: Many ORMs come with built-in features such as:
  Support for transactions
  Connection pooling
  Migrations
  Seeds
  Streams
• Performance

Question 3

What are the disadvantages of ORM?

Answer 3

• Performance Overhead: Expert SQL developers may write more performant queries than those generated by an ORM.
• Learning Curve: There is a learning curve associated with mastering any given ORM.
• Initial Configuration: Setting up an ORM can be complex and time-consuming.
• Abstraction Drawbacks: Over-reliance on ORM can lead to a lack of understanding of underlying database mechanics and SQL.

Question 4

What is Entity Framework?

Answer 4

Entity Framework is an object-relational
mapper (ORM) that enables .NET developers to work with a database using .NET objects.

It eliminates the need for most of the
data-access code that developers usually need to write.

Question 5

What is the Entity Data Model?

Answer 5

Contains model classes and their relationships, independent of the database table design. Representing the entities and relationships in a way that is familiar to object-oriented developers.

Question 6

What is the Storage Model?

Answer 6

Represents the underlying database schema including tables, views, stored procedures, relationships, and keys. Reflecting actual database designs.

Question 7

What are mappings?

Answer 7

Information about how the conceptual model is mapped to the storage model.
Enables EF to perform CRUD operations by transforming LINQ queries into SQL commands and converting database results back into entity objects.

Question 8

What is the Context Class in Entity Framework?

Answer 8

Represents a session with the underlying database, allowing for CRUD operations.

Question 9

What is the Model-First approach>

Answer 9

Create entities, relationships, and inheritance hierarchies on a visual designer in Visual Studio. Generate entities, context class, and database script from the visual model.

Question 10

What is an entity in Entity Framework?

Answer 10

A class that maps to a database table

Question 11

How does Entity Framework map an entity to a database table?

Answer 11

By including the entity as a DbSet<TEntity> type property in the DbContext class</TEntity>

Question 12

What are the components of the Entity Data Model (EDM)?

Answer 12

Conceptual model, storage model, and mappings.

Question 13

In EF Core, which approach is mainly targeted and why?

Answer 13

Code-First, because it allows creating a database and tables using migration based on domain classes.

Question 14

What are the two types of entities in Entity Framework?

Answer 14

POCO Entities and Dynamic Proxy Entities.

Question 15

What is a POCO (Plain Old CLR Object) Entity?

Answer 15

A POCO entity is a class that doesn’t depend on any framework-specific base class.

Question 16

What is Dynamic Proxy Entity?

Answer 16

Dynamic Proxy is a runtime proxy class which wraps POCO entity.

Question 17

What are the three approaches with Entity Framework?

Answer 17

Database-First, Code-First, Model-First

Question 18

What is the Database-First approach?

Answer 18

In the database-first development approach, you generate the context
and entities for the existing database using EDM wizard integrated in
Visual Studio.

Question 19

What is the Code-First approach?

Answer 19

Use this approach when you do not have an existing database for your
application.

In the code-first approach, you start writing your entities (domain
classes) and context class first and then create the database from
these classes using migration commands.

Question 20

What is the Model-First Approach?

Answer 20

Use this approach when you do not have an existing database for your
application.

In the code-first approach, you start writing your entities (domain
classes) and context class first and then create the database from
these classes using migration commands.

Question 21

What two approaches does EF Core support?

Answer 21

Code-First and Database-First.