What tools or libraries are used to form database queries?

• JDBC (Java Database Connectivity) - a standard API for working with databases in Java. It allows establishing connections, executing SQL queries, and processing results.
• ORM (Object-Relational Mapping) layer:
  • Hibernate - a popular framework providing high-level abstraction for database interaction. It allows working with Java objects instead of SQL.
  • JPA (Java Persistence API) - a specification defining a standard way for ORM in Java. Hibernate is one of its implementations.
  • EclipseLink - another implementation of JPA.
• Data access frameworks:
  • Spring Data - provides high-level abstractions and repositories to simplify data operations, often used in conjunction with JPA/Hibernate.
  • MyBatis - a framework for mapping SQL operators to Java methods. It allows full control over SQL.

Example of using JDBC:

// JDBC
try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
     Statement stmt = conn.createStatement();
     ResultSet rs = stmt.executeQuery("SELECT * FROM mytable")) {
    while (rs.next()) {
        // Process results
    }
} catch (SQLException e) {
    e.printStackTrace();
}

Example of using JPA/Hibernate:

// JPA/Hibernate
EntityManagerFactory emf = Persistence.createEntityManagerFactory("my-persistence-unit");
EntityManager em = emf.createEntityManager();

try {
    em.getTransaction().begin();
    // CRUD operations on objects
    em.getTransaction().commit();
} catch (Exception e) {
    em.getTransaction().rollback();
} finally {
    em.close();
    emf.close();
}