By the JDBC url, it's looks like you're trying to connect to a Derby server vs. an embedded instance. If you are trying to connect to a server instance, here are some considerations:
- did you start the server yourself, did mydb already exists?
- if not, did you pass in the correct params to create (e.g. ;create=true)
example: jdbc:derby://localhost:1527/dbname;create=true
- if mydb did exists, are you pointing the server to the correct location?
- also, depending on what was used to start derby (e.g. embedded vs network driver) default database locations are different as well. You can read about it here
Basically the exception you're getting is that Derby's saying it can't find your database - it's basically a path issue.