XML Unleashed

Chapter 22. Using XSL Patterns and XQL

In This Chapter

• Requirements of a Query Language

• XML Query Language (XQL)

• The Syntax of XQL

• XQL: Implementations and Other Resources

• XSLT Patterns

• Using DOM

• Hand-Rolled Functions

At its simplest level, an XML query can be considered any inquiry about the content of a document. At a slightly deeper level, it can be considered a method that returns information about a document. The obvious analogy is to SQL, the language that is used to query Random Access DataBase Management Systems (RADBMS). A SQL query returns a new recordset, constructed from the database, which contains records of the required information. An XQL query should return a new, well-formed XML document constructed from the old document. This chapter ...