Nexista's database support uses XML for SQL queries, and accepts XPath strings as parameter values for prepared statements. Problem is when you want to access and array of node local-name values, as only the first matching node name is returned. I ran into this problem when using key-value-pairs, and I was trying to use the name of an element node as a value in the SQL query. I ended up using something much simpler that has a clear dependency, so its not a big deal. Here's the scenario: A form is created using titles and keys from an XML document, and the XML document is used again to supply the keys for the SQL query. I was afraid that the keys and values would get mis-matched, but so far its been fine, even if I switch around the order of the XML nodes. See PBooks database abstractor for an example of where this issue comes up.