Introduction to XQuery
XQuery is to XML what
SQL is to database tables.
XQuery is designed to query XML data - not just
XML files, but anything that can appear as XML, including databases.
What You Should Already Know
Before you continue you should have a basic understanding of the following:
- HTML / XHTML
- XML / XML Namespaces
- XPath
If you want to study these subjects first, find the tutorials on our
Home page.
What is XQuery?
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- XQuery is the language for querying XML data
- XQuery for XML is like SQL for databases
- XQuery is built on XPath expressions
- XQuery is supported by all major databases
- XQuery is a W3C Recommendation
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XQuery is About Querying XML
XQuery is a language for finding and extracting elements and attributes from XML
documents.
Here is an example of a question that XQuery could solve:
"Select all CD records with a price less than $10 from the CD collection
stored in the XML document called cd_catalog.xml"
XQuery and XPath
XQuery 1.0 and XPath 2.0 share the same data model and support the same functions
and operators. If you have already studied XPath you will have no problems with
understanding XQuery.
You can read more about XPath in our XPath Tutorial.
XQuery - Examples of Use
XQuery can be used to:
- Extract information to use in a Web Service
- Generate summary reports
- Transform XML data to XHTML
- Search Web documents for relevant information
XQuery is a W3C Recommendation
XQuery is compatible with several W3C standards, such as XML, Namespaces,
XSLT, XPath, and XML Schema.
XQuery 1.0 became a W3C Recommendation January 23, 2007.
To read more about the XQuery activity at W3C, please read our
W3C Tutorial.
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