Saving and Retrieving Data with AJAX
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In this first part of a four-part series, you'll learn how to make your ASP.NET applications featuring AJAX do some of the most important functions: save, retrieve, and change data. This article is excerpted from chapter four of
Learning ASP.NET 2.0 with AJAX: A Practical Hands-on Guide, written by Jesse Liberty, Dan Hurwitz and Brian MacDonald (O'Reilly, 2007; ISBN: 0596513976). Copyright © 2007 O'Reilly Media, Inc. All rights reserved. Used with permission from the publisher. Available from booksellers or direct from O'Reilly Media.
So far, you’ve seen how to make good-looking web pages with clever and useful controls. You know how to change the appearance of the page in response to user selections, and how to use AJAX to enhance the performance of your application. But the applications you’ve made so far have been limited in what they can actually do. In this chapter we add the most frequently sought after functionality: the ability to retrieve, change and store data.
Think about the web sites you visit most often, and you’ll find that almost all of them have one thing in common—they interact with persistent data. Persistent data is data that survives a single session; data that you expect will be there the next time you visit. In fact, it may even be data that can have significant financial consequences.
Shopping sites have databases to track their inventories and customer transactions. News sites keep databases with articles and photos in them, perhaps referenced by topic and date. Search engines use unimaginably large (and wicked-fast) databases.
Nearly every real-world commercial web application must be able to perform the four essential “CRUD” interactions with a database: Create, Read, Update, and Delete.
Fortunately, ASP.NET provides controls that make it easy and fast to perform these essential activities. We will demonstrate these interactions with SQL Server Express (or its big brother, SQL Server) but they work equally well—or nearly so—with Microsoft Access and most commercial databases. In theory, you can interact with virtually any collection of data or with XML files, but that is an advanced topic we won’t go into here.
Along the way we’ll show you enough about database interactions that even if you’ve never used a relational database, such as SQL Express, you’ll have little trouble working with one through your web application.
Next: Getting Data from a Database >>
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 This article is excerpted from chapter four of Learning ASP.NET 2.0 with AJAX: A Practical Hands-on Guide, written by Jesse Liberty, Dan Hurwitz and Brian MacDonald (O'Reilly, 2007; ISBN: 0596513976). Check it out today at your favorite bookstore. Buy this book now.
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