With XQuery becoming the standard language for querying XML, and the relational SQL platform being recognized as an important platform to store and process XML, the SQL/XML standard is integrating XML query capability into the SQL system by introducing new SQL functions and constructs such as XMLQuery() and XMLTable. This paper discusses the Oracle XMLDB XQuery architecture for supporting XQuery in the Oracle ORDBMS kernel which has the XQuery processing tightly integrated with the SQL/XML engine using native XQuery compilation, optimization and execution techniques.