The eXtensible Markup Language (XML) started its life as replacement for the immens popularly but limited HTML-format. In time, it became apparent that XML was even more useful "outside the browser" and that it was extremely suitable as a format for data interchange and data storage. The popularity and wide-spread use of XML has led to a large and continuously growing amount of XML documents and a strong demand for efficient storage, query and retrieval solutions.

XQuery is a technology under development by the World Wide Web Consortium (W3C) that's designed to query collections of XML data -- not just XML files, but anything that can appear as XML, including relational databases. XQuery has broad support from IBM, Microsoft, and Oracle as well as application server vendors such as BEA and Software AG.

What is XQuery? Per Bothner. The World Wide Web Consortium is working on finalizing
the specification for XQuery, aiming for a final release late 2002. ...

The mission of the XML Query project is to provide flexible query facilities to extract data from real and virtual documents on the World Wide Web, therefore finally providing the needed interaction between the web world and the database world. Ultimately, collections of XML files will be accessed like databases. The ambitious task of the XML Query (XQuery) Project is therefore to develop the first world standard for querying web documents, following the incredibly successful discussion started at the QL'98 event. However, the XML-Query (XQuery) project is all-around, and also includes in its efforts not only the standard for querying XML documents, but also the next-generation standards for doing XML selection (XPath2), for doing XML serialization, for doing Full-Text Search, for providing a possible functional XML Data Model, and for providing a standard set of functions and operators for manipulating web data.

XQuery Questioned

XML developers contend that the overlap between XML Query and XSLT is so great that they aren't separate languages at all."

The XML-Deviant asks whether the XQuery specification should be refactored, and whether it should be released without specifying significant parts of the expected feature set? "

XQuery is a language from the W3C designed to query and format XML data. Our overview article gives you the lowdown on XQuery and further resources for learning more about it."

XQuery is a language from the W3C designed to query and format XML data. Our overview article gives you the lowdown on XQuery and further resources for learning more about it."

XML Query (XQuery) is designed to be a language in which queries are concise and easily understood. It is also flexible enough to query a broad spectrum of XML information sources, including both databases and documents.

In this installment of Practical XQuery I continue to discuss practical uses of XQuery, focusing this time on interactive web page generation. The sample application will display a list of books; based on user input, it will also display detailed information about the selected title.

The XQuery/XSLT working group released another set of Working Drafts on August 22, 2003. This article is my attempt to summarize the significant changes in the new drafts. Note that there is no new version of either the Data Model or Functions and Operators specifications, which were released to Last Call in May.

In this article we will show to to write and install a very simple web application written in the XQuery language. We will also show you how errors are handled, and how you can debug them. Our application uses the servlet extension of Qexo (version 1.7beta2 or later), a free software implementation of XQuery.

Learn to use XQuery conditional and quantified expressions to filter and select data, and to modify query results by including custom functions.

Learn how to use XQuery's FLWR (for, let where, and return) expressions to process and restructure data from one or more documents

The XQuery data model recognizes seven types of nodes. Learn how to take advantage of the data model in XQuery expressions

XML blurs the distinctions between databases, documents, and messages, but it needs a powerful and elegant query language to reach its full potential.  XQuery intends to be that language.

XQuery is a language from the W3C designed to query and format XML data. Our overview article gives you the lowdown on XQuery and further resources for learning more about it.