Apress - Pro SQL Server 2008 XML

Introduction

Back in 1999, I was working for a dot-com when I was first exposed to the interesting new technology known as XML. My imagination ran wild, and I immediately began working on dozens of applications for XML, like custom reporting from our legacy inventory system and Web-based business-to-business ordering. I was as excited as a kid on Christmas morning! My excitement about XML in those early days began to fade as I quickly ran into its limitations, however. For one thing, the basic XML standard did not define a type system. All content in XML is character data—strings. This meant that I needed to not only convert string data to the correct data type in my own applications, but I also had to validate the content and handle boatloads of potential exceptions in each application.

Another thing that bothered me was the strangely cryptic and underpowered Document Type Definition (DTD) system, the primary means of constraining XML document structure a d content. Again, the majority of structure and content validation became the responsibility of the application, making it even more complicated. And the fact that querying XML data required inefficient loops or event-based parsing and comparisons didn’t help matters much. Fortunately for us, XML has matured with the introduction of standards for constraining and typing XML data and efficiently querying XML content. Several XML-based standards have also been introduced to allow efficient and convenient data sharing across platforms. With SQL Server 2008, Microsoft has taken a different approach to the concept of the “database.” Rather than confining themselves to a basic relational model, Microsoft has taken the stance that your data should be accessible and manageable in all its glorious (and not so glorious) forms. While relational data remains king, XML is the cornerstone of disparate data integration. This book provides detailed information on XML from the SQL Server 2008 perspective.

I’ll discuss several aspects of SQL Server 2008 XML, including the XML functionality built right into SQL Server, as well as how to access SQL Server functionality that is not built into T-SQL. I’ll even look at client-side XML technologies that are important to SQL Server/XML–based application design. In all, I hope you find this book enjoyable and useful in designing and implementing your own SQL Server and XML-based applications.