Most of the Derby tools are JDBC applications. A JDBC
application is one that uses the classes in the java.sql package
to interact with a DBMS. When you work with JDBC applications,
you need to know about several concepts. The most basic is the
connection. A JDBC connection is the object through which
commands are sent to the Derby engine and responses are returned
to the program. Establishing a connection to a specific database
is done by specifying a appropriate database URL. The following
sections provide background information to help in understanding
the Derby database connection URL.