Generate XML using Oracle XML schema
It is fairly direct to push an already existing select to XML: http://docs.oracle.com/cd/B19306_01/appdev.102/b14259/xdb13gen.htm#i1028612

Creating XML is part of the basic SQL specifications and is available on most servers. You can check out SQL server's version of it here: http://blog.sqlauthority.com/2009/02/12/sql-server-simple-example-of-creating-xml-file-using-t-sql/