Both SQL and JDBC are standardised. In theory this means that if we have been careful to stick to the well-recognised parts of the standards then we should be able to switch to a different DBMS without any problems.

Let's try this now. We will switch to a DBMS named H2. H2 is written in Java and can ran in many different modes including being embedded into a Java application. That is how we are going to run it --- embedded into the application.