Connecting to a database and then executing good old SQL, though simplistic and straightforward, is not the most convenient way to operate on the data, map it in a set of domain objects, and manipulate the relational content. This is why multiple frameworks emerged to aid you with mapping the data from tables to objects, better known as object-relational mapping (ORM). The most notable example of such a framework is Hibernate.

In the previous example, we covered how to set up a connection to a database and configure the settings for the username and password, and we also discussed which driver to use, and so on. In this recipe, we will enhance our application by adding a few entity objects that define the structure of the data in the database and a CrudRepository interface to access the data.

As our application is a book-tracking catalogue, the obvious domain objects would be Book, Author, Reviewers, and Publisher.