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배워요!

JPA의 기본기를 탄탄하게 다질 수 있습니다.

JPA의 내부 동작 방식을 이해할 수 있습니다.

객체와 DB 테이블을 올바르게 설계하고 매핑할 수 있습니다.

실무에서 자신있게 JPA를 사용할 수 있습니다.

인프런 강의 :  https://www.inflearn.com/course/ORM-JPA-Basic

강의 자료 : 

https://github.com/braverokmc79/jpa-basic-lecture-file

소스 :

https://github.com/braverokmc79/jpa-shop

[4] 연관관계 매핑 기초

13.  단방향 연관관계

강의:

https://www.inflearn.com/course/lecture?courseSlug=ORM-JPA-Basic&unitId=21696&tab=curriculum

소스 :

https://github.com/braverokmc79/ex-jpa-13-1

Member

package jpashop.home.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
public class Member {

	@Id @GeneratedValue
	private Long id;
	
	@Column(name="USERNAME")
	private String username;
	
	@ManyToOne
	@JoinColumn(name = "TEAM_ID")
	private Team team;
	
	public Member() {
		
	}
}

Team

package jpashop.home.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
public class Team {


	@Id @GeneratedValue
	@Column(name="TEAM_ID")
	private Long id;
	
	private String name;
	
}

JpaMain

package jpashop.home;


import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

import jpashop.home.domain.Member;
import jpashop.home.domain.Team;

public class JpaMain {
	public static void main(String[] args) {
		EntityManagerFactory emf=Persistence.createEntityManagerFactory("hello");
		
		EntityManager em=emf.createEntityManager();
		
		//JPA 의 모든 데이터 변경은  트랜잭션 안에서 실행 되어야 한다.
		EntityTransaction tx=em.getTransaction();
		tx.begin();
			
		try {
			
			Team team =new Team();
			team.setName("TeamA");
			em.persist(team);
			
			Member member =new Member();
			member.setUsername("member1");
			member.setTeam(team);
			
			em.persist(member);
			
			Team findTeam=member.getTeam();
			System.out.println(" findTeam  : "  + findTeam.getName());
			
			tx.commit();
		}catch(Exception e) {
			tx.rollback();
		}finally {
			em.close();
		}
	
		
		emf.close();	
	}
	
	
}

14.  단방향 연관관계

강의:

https://www.inflearn.com/course/lecture?courseSlug=ORM-JPA-Basic&unitId=21697&tab=curriculum

소스 :

https://github.com/braverokmc79/ex-jpa-13-1

Team

package jpashop.home.domain;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
public class Team {


	@Id @GeneratedValue
	@Column(name="TEAM_ID")
	private Long id;
	private String name;
	
	/**★★★외래키가 있는 곳을 주인으로 정해라!
	 * 객체와 테이블이 관계를 맺는 차이
	 * 객체 연관관계 =2개
	 * mappedBy 는 Many 테이블의 외래키값을 넣으면 된다.
	 * 여기서는 Member 테이블의 team 이 외래키이다.
	 * 
	 * 조회만 가능하고 외래키의 값의 업데이트는 member 의 team 에서 업데이트 가능하다.
	 */
	@OneToMany(mappedBy = "team")
	private List<Member> members=new ArrayList();
	

}

15.  양방향 연관관계와 연관관계의 주인 2 - 주의점, 정리

강의:

https://www.inflearn.com/course/lecture?courseSlug=ORM-JPA-Basic&unitId=21698&tab=curriculum

★ 연관관계의 주인은 외래 키의 위치를 기준으로 정해야함

16.  실전 예제 2 - 연관관계 매핑 시작

강의:

https://www.inflearn.com/course/lecture?courseSlug=ORM-JPA-Basic&unitId=21699&tab=curriculum

Member

package jpashop.home.domain;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
public class Member {

	@Id @GeneratedValue
	@Column(name="MEMBER_ID")
	private Long id;
	private String name;
	private String city;
	private String street;
	private String zipcode;
	
	
	//mappedBy 는 연관 관계의 주인은 누구? member
	@OneToMany(mappedBy = "member")
	private List<Order> orderList=new ArrayList<>();
	
	
}

Order

package jpashop.home.domain;

import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EnumType;
import javax.persistence.Enumerated;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
@Table(name="ORDERS")  //ORDER DB 에서 예약어로 사용되는 경우 많아서 ORDERS 
public class Order {
  
	@Id @GeneratedValue
	@Column(name="ORDER_ID")
	private Long id;
	
	@ManyToOne
	@JoinColumn(name="MEMBER_ID")
	private Member member;	
	
	@OneToMany(mappedBy = "order")
	private List<OrderItem> orderItems=new ArrayList<>();
	
	
	private LocalDateTime orderDate;
	
	//ORDINAL 숫자 타입으로 하면 순서가 꼬이므로 무저건 String 한다
	@Enumerated(EnumType.STRING)
	private OrderStatus status;

	//양방향 연관 관계 설정
	public void addOrderItem(OrderItem orderItem) {
		orderItems.add(orderItem);
		orderItem.setOrder(this);
	}
	
	
	
}

OrderItem

package jpashop.home.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
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 oderPrice;
	
	private int count;
	
}

Item

package jpashop.home.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

import lombok.Getter;
import lombok.Setter;

@Entity
@Getter
@Setter
public class Item {

	@Id @GeneratedValue
	@Column(name="ITEM_ID")
	private Long id;
	
	private String name;
	private String price;
	private int stockQuantity;
}

OrderStatus

package jpashop.home.domain;

public enum OrderStatus {
	ORDER, CANCEL
}

JpaMain

package jpashop.home;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

import jpashop.home.domain.Order;
import jpashop.home.domain.OrderItem;

public class JpaMain {
	public static void main(String[] args) {
		EntityManagerFactory emf=Persistence.createEntityManagerFactory("hello");
		
		EntityManager em=emf.createEntityManager();
		
		//JPA 의 모든 데이터 변경은  트랜잭션 안에서 실행 되어야 한다.
		EntityTransaction tx=em.getTransaction();
		tx.begin();
			
		try {
			
			Order order =new Order();
			order.addOrderItem(new OrderItem());
			
			
			
			tx.commit();
		}catch(Exception e) {
			tx.rollback();
		}finally {
			em.close();
		}
	
		
		emf.close();	
	}
	
	
}