Spring Data JPA

Spring Data JPA eliminates boilerplate code for database operations.

Repository Pattern

Instead of writing DAOs, extend repository interfaces.

JpaRepository

public interface UserRepository extends JpaRepository<User, Long> {
    // That's it! CRUD methods are auto-generated
}

Auto-Generated Methods

• save(entity)
• findById(id)
• findAll()
• deleteById(id)
• count()

Custom Queries

Method Name Queries

Spring generates SQL from method names!

public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findByName(String name);
    List<User> findByEmailContaining(String email);
    User findByEmailAndName(String email, String name);
}

@Query Annotation

@Query("SELECT u FROM User u WHERE u.age > :age")
List<User> findUsersOlderThan(@Param("age") int age);

Pagination & Sorting

// Pagination
Pageable pageable = PageRequest.of(0, 10); // Page 0, size 10
Page<User> users = userRepository.findAll(pageable);

// Sorting
Sort sort = Sort.by("name").ascending();
List<User> sorted = userRepository.findAll(sort);

Quiz