Discovering SQL: A Hands-On Guide for Beginners

SQL AND XML

eXtensible Markup Language (XML) falls right in the middle between the rigor of the structured data and perceived chaos of unstructured data. On one hand, as you will see, it has a well-defined structure and rules; on the other hand, it mixes in a “free-text” approach.

It is a popular language of information exchange and is well on its way to becoming the de facto standard for web services, as well as more traditional software applications. In recent years, there was a shift by users from proprietary document formats to those that are open and not controlled by any commercial entity. The vendors took notice: Starting with Microsoft Office 2007, the Office Open XML file format (OpenXML or OOXML) has become the default Microsoft Office file format as well as the international ECMA-376 standard. Several countries, most notably in Europe, have also announced adoption of the Open Office XML on national level. The hugely popular open source OpenOffice.org implemented its own, somewhat different, XML-based format called Open Document Format (ODF, governed by the OASIS consortium) for its file (though, beginning with version 3.0 it is also interoperable with OOXML), as did many other software vendors around the world. While particulars of the implementations might be different, they are all based on XML principles.

The versatility of XML comes from its venerable predecessor: Standard Generalized Markup Language (SGML). The original SGML was conceived as a means for representing ...