Connecting to databases outside the system directory
You can also connect to databases in other directories (including
subdirectories of the system directory) by specifying a relative or absolute
path name to identify the database. The way you specify an absolute path is
defined by the host operating system.
Using the connection URL as described here, you can connect to databases
in more than one directory at a time.
Note: Once connected, such a database becomes a part of the Derby system,
even though it is not in the system directory. This means that it takes on
the system-wide properties of the system and no other instance of Derby should
access that database. It is recommended that you connect to databases only
in the system directory.