Derby lets you create table functions. Table functions are functions which package up external data to look like Derby tables. The external data can be an XML file, a table in a foreign database, a live data feed--in short, any information source that can be presented as a JDBC ResultSet.
Derby-style table functions let you efficiently import foreign data into Derby tables. Table functions let you join Derby tables with any of the following data sources:
See "CREATE FUNCTION statement" in the Derby Reference Manual for the complete syntax needed to declare Derby-style table functions. The following topics provide information on how to write Java methods which wrap foreign data sources inside ResultSets.