Chapter 18

Operating on XML Data with SQL


Bullet Using SQL with XML

Bullet Exploring the relationship between XML, databases, and the Internet

Starting with SQL:2008, ISO/IEC standard SQL supports XML. XML (eXtensible Markup Language) files have become a universally accepted standard for exchanging data between dissimilar platforms. With XML, it doesn’t matter if the person you’re sharing data with has a different application environment, a different operating system, or even different hardware. XML can form a data bridge between the two of you.

How XML Relates to SQL

XML, like HTML, is a markup language, which means that it’s not a full-function language such as C++ or Java. It’s not even a data sublanguage such as SQL. However, unlike those languages, it is cognizant of the content of the data it transports. Where HTML deals only with formatting the text and graphics in a document, XML gives structure to the document’s content. XML itself does not deal with formatting. To do that, you have to augment XML with a style sheet. As it does with HTML, a style sheet applies formatting to an XML document.

The structure of an XML document is provided by its XML schema, which is an example of metadata (data that describes data). An XML schema describes where elements may occur in ...

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