연관관계 매핑 기초 - 실전예제

실습

1. 관계도

 

2. ERD

3. 엔티티 상세

4. 참고사항

    1) 테이블의 N:M 관계는 중간 테이블을 이용해서 1:N, N:1 

    2) 실전에서는 중간 테이블이 단순하지 않다. 

    3) @ManyToMany는 제약: 필드 추가X, 엔티티 테이블 불일치

    4) 실전에서는 @ManyToMany 사용X

5. 코드

@Entity
public class Category {
	@Id
	@GeneratedValue
	private Long id;
	
	private String name;
	
	@ManyToOne
	@JoinColumn(name = "PARENT_ID")
	private Category parent;
	
	@OneToMany(mappedBy = "parent")
	private List<Category> child = new ArrayList<>();
	
	@ManyToMany
	@JoinTable(name ="CATEGORY_ITEM", 
				joinColumns = @JoinColumn(name ="CATEGORY_ID"),
				inverseJoinColumns = @JoinColumn(name = "ITEM_ID"))
	private List<Item> items = new ArrayList<>();
	
	Getter(), Setter() ...
}

 

@Entity
public class Delivery {
	@Id
	@GeneratedValue
	private Long id;

	private String city;
	private String street;
	private String zipcode;
	private DeliveryStatus status;

	@OneToOne
	@JoinColumn(name = "delivery")
	private Orders order;
    
    Getter(), Setter() ...
 }

 

public enum DeliveryStatus {
}

 

@Entity
public class Item {
	@Id
	@GeneratedValue
	@Column(name="ITEM_ID")
	private Long id;

	private String name;
	private int price;
	private int stockQuantity;
	
	@ManyToMany(mappedBy = "items")
	private List<Category> categories = new ArrayList<>();
    
    Getter(), Setter() ...
}

 

@Entity
public class Member {
	@Id
	@GeneratedValue
	@Column(name = "MEMBER_ID")
	private Long id;
	@Column(name = "USERNAME")
	private String name;
	private int age;
	@OneToMany
	@JoinColumn(name = "member")
	private List<Order> orders = new ArrayList<>();
    
    Getter(), Setter() ...
}

 

@Entity
@Table(name = "ORDERS")
public class Order {

	@Id
	@GeneratedValue
	@Column(name = "ORDER_ID")
	private Long id;

	@ManyToOne
	@JoinColumn(name = "MEMBER_ID")
	private Member member;
	
	@OneToOne
	@JoinColumn(name = "DELIVERY_ID")
	private Delivery delivery;
	
	@OneToMany(mappedBy = "order")
	private List<OrderItem> orderItems = new ArrayList<>();

	private LocalDateTime orderDate;

	@Enumerated(EnumType.STRING)
	private OrderStatus status;
    
    Getter(), Setter() ...
}

 

@Entity
public class OrderItem {
	@Id
	@GeneratedValue
	@Column(name = "ORDER_ITEM_ID")
	private Long id;

	@ManyToOne
	@JoinColumn(name = "ORDER_ID")
	private Order order;

	@ManyToOne
	@JoinColumn(name = "ITEM_ID")
	private Item item;

	private int orderPrice;
	private int count;
    
    Getter(), Setter() ...
}  

 

public enum OrderStatus {
	ORDER, CANCEL
}

 

public class JpaStudyApplication {

	public static void main(String[] args) {
		EntityManagerFactory emf = Persistence.createEntityManagerFactory("hello");

		EntityManager em = emf.createEntityManager();

		EntityTransaction tx = em.getTransaction();

		// 트랜잭션 시작
		tx.begin();

		try {
			tx.commit(); // [트랜잭션] 커밋
		} catch (Exception e) {
			tx.rollback();
		} finally {
			em.close();

		}
		emf.close();
	}
}