Nó cũng là một cột Identity (số tự động), và do đó, các kỹ thuật nhận dạng giá trị tài sản là Có. Tăng nhận dạng và các thuộc tính giống nhận dạng, mà bạn tìm thấy bằng cách mở rộng các mục nhập kỹ thuật nhận dạng, được thiết lập để 1 (các giá trị mặc định), | Chapter 4 As objects each one can expose properties methods and events. The SqlDataSource declared in this code exposes properties such as ID Connectionstring and SelectCommand and these can be set as you can see in the preceding code simply by declaring them as attributes on the element in the page. Methods that the objects expose allow you to execute specific functionality. For example you can force a data display control to bind to and display its source data by calling the DataBind method of that control. The event-driven nature of simply means that the objects that make up the platform expose events when specific actions occur. Effectively they send a message to any other objects that are listening for that event and these objects can then react to the event by executing the appropriate code. As an example a Button control on a Web page will raise a Click event when clicked and the page is submitted to the server. Code in the page can register to receive this event and react to it by for example displaying a message in the page. The pages you have created so far which include a data source control such as the SqlDataSource and a data display control such as the Gridview depend on the event-driven architecture of . When the client requests a page a series of events occurs within the page framework. Any data source controls on the page handle react to this event by fetching the data specified by the properties of the control and then call a method of the data display control to create the output you see on the page. In Chapter 5 you will see how you can react to events exposed by the GridView control and even other types of objects such as the Page itself. In later chapters you will see how you can create your own classes that plug into and work with the classes in the .NET Framework. About the GridView Control The examples you have seen so far that use a GridView control all depend on this control automatically generating the
