your database server is accepting TCP connections.
Check that your database server is running on the server address you think it is
Check for firewalls. Is there a port or ports being blocked between your application and the database?
Check that you are not having a security problem. Is your
application an Applet? If you are connecting to a database that is not
on the same physical box as your web server then you need to sign your
Check that you are using the right username and password
Check that the database user has the correct permissions and is
able to log in from the location you are attempting to log in from.
Check that you are using the correct driver for your database.
There often different versions of the same driver for the same database
but different versions of the database since the underlying proctocol
had some changes between versions.