barcode visual basic FiguRe 14-14 New objects created by generalization in .NET

Printer QR Code ISO/IEC18004 in .NET FiguRe 14-14 New objects created by generalization

but you can only delete one page of records at a time. If you need to delete 500 or more records, this might be a time-consuming process. In addition, you might want to set up an automated process where you delete old records from your database at a scheduled interval to keep the file size down. The bulk record deletion functionality is a good way to resolve these scenarios. You can start a bulk deletion job in one of two ways:

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To create a new application, select New Project from the File menu. This opens the )New Project dialog box, as shown in Figure 2-2.

As we examine the support within the .NET Framework for various types of data handling, it s important to understand some of the details of implementation. As you ll see, using the .NET Framework, you ll be able to use a great variety of objects to access data. All of this access, whether the underlying data is in an array, in a SQL Server database, or in an XML document, will have one thing in common: it will take place through the IEnumerator interface. Recall that interfaces are the definition of a set of behaviors that a class can agree to support. Although .NET doesn t allow multiple inheritance, it does allow a class to

differ significantly on your machine, particularly if you re using Windows, where the path layout will be entirely different, with the drive letter at the start and backslashes instead of forward slashes.

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within each currently active session. The structure and API of the three objects is similar, and all provide access using a familiar name/value notation. Session and Cache differ in that Session is a block of memory set aside for each user and Cache manages globally accessible data. The key difference between Application and Cache is the Cache object s support of item dependencies. Cache can remove cached items when certain events occur. First and foremost, it drops the least-used items if the Web server runs low on memory. You can also define item dependencies so cached items are removed after a specific duration of time, at a certain time, or when one or more files or cached items change. This characteristic makes the Cache object an important tool for building highly scalable, fast Web applications. One instance of the Cache class is created per application domain, and it shares the lifetime of the domain.

public partial class ThrowErrors : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void ButtonThrow404_Click(object sender, EventArgs e) { this.Response.Redirect("NonExistent.aspx"); } protected void ButtonThrowOther_Click(object sender, EventArgs e) { } }

Table 4-1: Debugging Events Debugging Event CREATE_PROCESS_DEBUG_EVENT Description This debugging event is generated whenever a new process is created in a process being debugged or whenever the debugger begins 149

Figure 2-10. Setting the default script location A second task is to disable some of the extensions that you do not need at this time. The advantage is reducing the start time for SQL Developer. For this book, you don t need any of the extensions, so unselect them all. You will be prompted for a restart. You should notice that SQL Developer restarts considerably faster than it did when you first started it.

Make it easy to find the end of a continuation line One problem with the approach shown above is that you can t easily find the end of each line. Another alternative is to put each argument on a line of its own and indicate the end of the group with a closing parenthesis. Listing 31-42 shows how it looks.

#region Web Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.Load += new System.EventHandler(this.Page_Load);

3.141592 This example demonstrates that constants have scope within the context of classes. The OtherPlanet class has its own definition of Pi. However, if you hadn t redefined it there, the original Pi would have been available to OtherPlanet, as the OtherPlanet class is defined within the global scope. The second section of the preceding example also demonstrates that you can interrogate constants within other classes directly. OtherPlanet::Pi refers directly to the Pi constant within OtherPlanet.