Db2 XQuery concepts

The following topics introduce basic XQuery concepts and describe how XQuery works with a Db2 database.

Introduction to XQuery
XQuery is a functional programming language that was designed by the World Wide Web Consortium (W3C) to meet specific requirements for querying and modifying XML data.
Comparison of XQuery to SQL
Db2 databases support storing well-formed XML data in a column of a table and retrieving the XML data from the database by using SQL, XQuery, or a combination of SQL and XQuery. Both languages are supported as primary query languages, and both languages provide functions for invoking the other language.
Retrieving Db2 data with XQuery functions
In XQuery, a query can call one of the following functions to obtain input XML data from a Db2 database: db2-fn:sqlquery and db2-fn:xmlcolumn.
XQuery and XPath data model
XQuery expressions operate on instances of the XQuery and XPath data model (XDM) and return instances of the data model.
Serialization of the XDM
The result of an XQuery expression, which is an instance of the XDM, can be transformed into an XML representation through a process called serialization.
XML namespaces and QNames
An XML namespace is a collection of names that is identified by a namespace URI. Namespaces provide a way of qualifying names that are used for elements, attributes, data types, and functions in XQuery. A name that is qualified with a namespace prefix is a qualified name (QName).
Language conventions
XQuery language conventions are described in the following topics.
Where to find more information about XQuery
See these resources for more information about the specifications on which Db2 XQuery is based.

Parent topic: XQuery reference