XQuery is the query language for XML and is officially defined by a W3C Recommendation document. The many benefits of XQuery include:
XQuery allows you to work in one common model no matter what type of data you're working with: relational, XML, or object data.
XQuery is ideal for queries that must represent results as XML, to query XML stored inside or outside the database, and to span relational and XML sources.
XQuery allows you to create many different types of XML representations of the same data.
XQuery allows you to query both relational sources and XML sources, and create one XML result.