Many-to-Many Bidirectional Relationship

In a bidirectional relationship, each side has a reference to the other. In our example, the Category class did not have any reference to the Tournament class. Now we will add a reference to the Tournament class so that the relationship can be navigated from both sides. This will have no effect on the underlying database structure. The join table tournament_catogories already has the foreign keys of both the tournament and category tables, and it is possible to write SQL queries to get tournaments associated with a category.