Triangle => Square

Has anyone here experimented with modelling XML (or some reasonable subset of the XML Information Set) as SQL tables? I know there are support for XML in some databases, but for those that don't have support, how'd you do it? [Actually the underlying database does support it, but the application platform over it does not.] I'm thinking the simplest solution is to have a nodeId, a nodeParentId, a nodeName, a nodeType (att, elem, text, cdata, pi, comment, ...) a nodeValue and possibly some more (maybe XS types). Binary nodes could be encoded as BLOB and output as Base64 encoded text. However, if you had such a structure it would be very convenient to also have an XPath implementation to query over it. That would be the next problem...