XML programming with SQL/XML and XQuery

Most business data are stored in relational database systems, and SQL (Structured Query Language) is used for data retrieval and manipulation. With XML (Extensible Markup Language) rapidly becoming the de facto standard for retrieving and exchanging data, new functionality is expected from traditional databases. Existing SQL applications will evolve to retrieve relational data as XML data using database or SQL ex-tensions for XML. New XML data will be stored, searched, and manipulated in the database as a "first class" citizen along with existing relational data. Furthermore, new applications will emerge that solely operate in terms of XML. These new XML applications operate on the same database using an XML query language, XQuery. In this paper, we describe an integrated database architecture that enables SQL applications with XML extensions as well as XQuery applications to operate on the same data. The architecture allows for a seamless flow from relational data to XML and back.