What was used for database interaction in the application?

To interact with databases in Java applications, the following are commonly used:

• JDBC (Java Database Connectivity) — a basic API for connecting and executing SQL queries.
• ORM frameworks, such as Hibernate or JPA, which allow working with the database through objects, simplifying code and transaction management.
• Spring Data — an extension over JPA that provides convenient repositories and methods for CRUD operations.

Example of using Spring Data JPA:

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findByLastName(String lastName);
}

This approach allows writing less code and focusing on business logic rather than SQL details.