SQL statements in JDBC are built using the createStatement method of a Connection object. Even classes running inside the server need to establish a connection to create a Connection object.
Establishing a connection from a server-side JDBC class is more straightforward than establishing an external connection. Because the user is already connected to the database, the class simply uses the current connection.
Server-side connection example code
How the server-side connection example differs
Running the server-side connection example