002. Basic (Single Entity with CRUD) - dkkahm/study-spring-jpa GitHub Wiki

@Entity
public class Course {

    @Id
    @GeneratedValue
    private Long id;

    private String name;

    public Course() {
    }

    public Course(String name) {
        this.name = name;
    }

    public Course(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    .... // getters and setters
}

@Repository
@Transactional
public class CourseRepository {

    @Autowired
    EntityManager em;

    public Course findById(Long id) {
        return em.find(Course.class, id);
    }

    public Course save(Course course) {
        if(course.getId() == null) {
            em.persist(course);
        } else {
            em.merge(course);
        }

        return course;
    }

    public void deleteById(Long id) {
        Course course = findById(id);
        em.remove(course);
    }

   Query query = em.createQuery("Select c From Course c")
   List resultList = query.getResultList();

   TypedQuery<Query> query = em.createQuery("Select c From Course c", Course.class)
   List<Course> resultList = query.getResultList();

   TypedQuery<Query> query = em.createQuery("Select c From Course c where name like '%100 Steps'", Course.class)
   List<Course> resultList = query.getResultList();

   @UpdateTimestamp
   private LocalDateTime lastUpdatedDate;

   @CreationTimestamp
   private LocalDateTime createdDate;

@NamedQueries(
    value= {
        @NamedQuery(name="query_get_all_courses", query="Select c From Course c"),
        @NamedQuery(name="query_get_100_step_courses", query="Select c From Course c where name like '%100 Steps'")
    }
)

    Query query = em.createNamedQuery("query_get_all_course", Course.class);

   Query query = em.createNativeQuery("SELECT * FROM COURSE", Course.class);

   Query query = em.createNativeQuery("SELECT * FROM COURSE where id = ?", Course.class);
   query.setParameter(1, 10001L);

   Query query = em.createNativeQuery("SELECT * FROM COURSE where id = :id", Course.class);
   query.setParameter("id", 10001L);

    Query query = em.createNativeQuery("Update COURSE set last_updated_date=sysdate()", Course.class)
    int numberOfRowsUpdated = query.executeUpdate();