tailieunhanh - Microsoft ADO .NET 4 Step by Step - p 30

Truy cập các thuộc tính của một thực thể thông qua một trường hợp đối tượng tiêu chuẩn Thêm, cập nhật, và xóa các nội dung cơ sở dữ liệu bằng cách thay đổi thuộc tính đối tượng Thực hiện các hành động truy vấn giống như sử dụng phương pháp tiêu chuẩn cuộc gọi | Chapter 16 Understanding Entities Through Objects After completing this chapter you will be able to Access the properties of an entity through a standard object instance Add update and delete database content by modifying object properties Carry out query-like actions using standard method calls One of the main advantages of the Entity Framework EF is that you can manage database content using standard .NET objects that reflect the conceptual nature of the data. Behind the scenes various XML models generated language code blocks and provider interactions make this possible. But the complexity exists solely to fulfill the promise of providing simplicity in handling the main business logic of your application. Imagine being able to modify the Name property of a Customer object in code and have that change propagate to the database all without having to write any of the code to make that happen. This chapter introduces Object Services the part of the Entity Framework that makes that promise a reality. This Framework layer makes the transition from database to model to objects or vice versa possible. In a way the Entity Framework is the Object Services layer because that layer is responsible for the core functionality of the Framework. Visual Studio makes working with the Framework easy because access to its functionality is enhanced by visual designers and Entity SQL scripts. This chapter focuses on the objects themselves you ll see how to add modify and remove them in a way that directly affects the external data store. Note The exercises in this chapter all use the same sample project which is a tool that provides editing features for a table of customers. While you will be able to run the application after each exercise the expected results for the full application might not appear until you complete all exercises in the chapter. Managing Entity Data Through Objects Object Services manages the entire lifetime of data through the Entity Framework from determining .