1. A method of producing output data from a database system in response to instructions from distributed user terminals, said method comprising steps of establishing a communications channel between a user terminal and said database system, wherein said database system includes a plurality of independent databases having a plurality of database schemas; supplying data from said database system to said connected user terminal to identify available relational data queries corresponding to pre-determined data mappings between said independent databases; returning data to said database system identifying a selected relational data query from said available selection; and implementing said selected query to produce output data from said database system.