Linking together two tables in XML using Xquery

[Mehint]

Hi,

I want to link together two tables of a database using Xquery. The db has been converted from a relational database to a hierarchical one.
The structure of the database is the following:
<VKCDB>
- <DBref>
- <row>
<dbref_id>DBref0</dbref_id>
<pdb_id />
<hssp_id>Q54397</hssp_id>
<mim_id>176262</mim_id>
<locus_id>3737</locus_id>
<mgd_id />
<interpro_id>IPR000210-BTB_POZ IPR005821-Ion_trans IPR001622-K IPR003091-K_channel IPR003131-K_tetra IPR004049-KV12channel IPR003968-Kv_channel IPR005820-M IPR003972-Shaker_channel</interpro_id>
<pfam_id>PF00520-ion_trans PF02214-K_tetra</pfam_id>
<prints_id>PR00169-KCHANNEL PR01509-KV12CHANNEL PR01491-KVCHANNEL PR01496-SHAKERCHANEL</prints_id>
<smart_id>SM00225-BTB</smart_id>
</row>
</DBref>
-<reference>
- <row>
<ref_id>Ref0</ref_id>
<author>Ramaswami M., Gautam M., Kamb A., Rudy B., Tanouye M.A., Mathew M.K.</author>
<title>Human potassium channel genes: molecular cloning and functional expression</title>
<journal>Mol. Cell. Neurosci. 1:214-223(1990).</journal>
<position />
<comment>TISSUE=Brain</comment>
<medline_id />
<pubmed_id />
</row>
</reference>
</VKCDB>
The two tables DBref and reference should be linked together using the attribute dbref_id on one side and ref_id on the other side.
Has someonean idea of how to solve this or where I can find something on it?

Best Regards,
Isabella