Programming Entity Framework: DbContext

Chapter 2. Querying with DbContext

There are two things that almost every application that accesses a database has in common: the need to retrieve data from the database and to save changes to that data back into the database. Over the next two chapters you will see how the DbContext API makes it easy to achieve these tasks using the Entity Framework. The focus of this chapter will be on retrieving data from the database.

One of the great benefits of using an Object Relational Mapper (ORM), such as Entity Framework, is that once we have set up the mapping, we can interact with our data in terms of the objects and properties that make up our model, rather than tables and columns. When querying for objects, this means we no longer need to know how to write queries using the SQL syntax of our database.

Writing Queries with LINQ to Entities

Entity Framework queries are written using a .NET Framework feature known as Language Integrated Query, or LINQ for short. As the name suggests, LINQ is tightly integrated with the .NET programming experience and provides a strongly typed query language over your model. Strongly typed simply means that the query is defined using the classes and properties that make up your model. This provides a number of benefits such as compile-time checks to ensure your queries are valid and the ability to provide IntelliSense as you write your queries.

LINQ is a general query framework and isn’t specific to Entity Framework, or even databases for that matter. A LINQ ...