A data processing system receives data in a first format utilizing a markup language such as eXtensible Markup Language (XML), and stores the data in a different, relational database format involving multiple tables and columns, etc. The system translates subsequent query input expressed in the first format to prepare representative query instructions in SQL or another query language compatible with relational data, and thereafter executes the prepared instructions upon data in the relational database. The system outputs results of the query in format dictated by the query input.