JPQL 엔티티 직접 사용(Direct Use Of Entity)

엔티티 직접 사용#

기본 키 값#

JPQL에서 엔티티를 직접 사용하면 SQL로 어떠한 쿼리가 실행되는 지에 대한 정리 입니다.

COUNT(m) 같은 SQL 함수에서 엔티티를 직접 사용했을때, SQL에서 해당 엔티티의 식별자인 기본 키 값을 사용하게됩니다.

[JPQL]

SELECT COUNT(m.id) FROM Member M // 엔티티의 아이디를 사용

SELECT COUNT(m) FROM Member M // 엔티티를 직접 사용

[SQL] (둘다 같은 다음 SQL 실행)

SELECT COUNT(m.id) as CNT FROM Member m

엔티티를 파라미터로 전달

String jpql = "SELECT m FROM Member m WHERE m WHERE m = :member";
List resultList = em.createQuery(jqpl)
                    .setParameter("member", member)
                    .getResultList();

JpqlMain.java

            Team team1 = new Team();
            team1.setName("팀A");
            em.persist(team1);

            Team team2 = new Team();
            team2.setName("팀B");
            em.persist(team2);

            Team team3 = new Team();
            team3.setName("팀C");
            em.persist(team3);

            Member member1 = new Member();
            member1.setUsername("회원1");
            member1.setAge(31);
            member1.changeTeam(team1);
            member1.setType(MemberType.USER);
            em.persist(member1);

            Member member2 = new Member();
            member2.setUsername("회원2");
            member2.setAge(32);
            member2.changeTeam(team1);
            member2.setType(MemberType.USER);
            em.persist(member2);

            Member member3 = new Member();
            member3.setUsername("회원3");
            member3.setAge(33);
            member3.changeTeam(team2);
            member3.setType(MemberType.USER);
            em.persist(member3);

            Member member4 = new Member();
            member4.setUsername("회원4");
            member4.setAge(34);
            member4.changeTeam(team3);
            member4.setType(MemberType.USER);
            em.persist(member4);

            em.flush();
            em.clear();

            String sQuery = "SELECT m FROM Member m WHERE m = :mmbr";

            List<Member> resultList = em.createQuery(sQuery, Member.class)
                    .setParameter("mmbr",member1)
                    .getResultList();


            for(Member member : resultList){
                System.out.println("name = " + member.getUsername()+ ", age = " + member.getAge());
            }

            tx.commit();

console

Hibernate: 
    /* SELECT
        m 
    FROM
        Member m 
    WHERE
        m = :mmbr */ select
            member0_.id as id1_0_,
            member0_.age as age2_0_,
            member0_.TEAM_ID as team_id5_0_,
            member0_.type as type3_0_,
            member0_.username as username4_0_ 
        from
            Member member0_ 
        where
            member0_.id=?
            
        
name = 회원1, age = 31

식별자를 직접 전달

String jpql = "SELECT m FROM Member m WHERE m.id = :memberId";
List resultList = em.createQuery(jqpl)
                    .setParameter("memberId", memberId)
                    .getResultList();

JpqlMain.java

            Team team1 = new Team();
            team1.setName("팀A");
            em.persist(team1);

            Team team2 = new Team();
            team2.setName("팀B");
            em.persist(team2);

            Team team3 = new Team();
            team3.setName("팀C");
            em.persist(team3);

            Member member1 = new Member();
            member1.setUsername("회원1");
            member1.setAge(31);
            member1.changeTeam(team1);
            member1.setType(MemberType.USER);
            em.persist(member1);

            Member member2 = new Member();
            member2.setUsername("회원2");
            member2.setAge(32);
            member2.changeTeam(team1);
            member2.setType(MemberType.USER);
            em.persist(member2);

            Member member3 = new Member();
            member3.setUsername("회원3");
            member3.setAge(33);
            member3.changeTeam(team2);
            member3.setType(MemberType.USER);
            em.persist(member3);

            Member member4 = new Member();
            member4.setUsername("회원4");
            member4.setAge(34);
            member4.changeTeam(team3);
            member4.setType(MemberType.USER);
            em.persist(member4);

            em.flush();
            em.clear();


            String sQuery = "SELECT m FROM Member m WHERE m.id = :mmbrId";

            List<Member> resultList = em.createQuery(sQuery, Member.class)
                    .setParameter("mmbrId",member1.getId())
                    .getResultList();


            for(Member member : resultList){
                System.out.println("name = " + member.getUsername()+ ", age = " + member.getAge());
            }

            tx.commit();

console

Hibernate: 
    /* SELECT
        m 
    FROM
        Member m 
    WHERE
        m.id = :mmbrId */ select
            member0_.id as id1_0_,
            member0_.age as age2_0_,
            member0_.TEAM_ID as team_id5_0_,
            member0_.type as type3_0_,
            member0_.username as username4_0_ 
        from
            Member member0_ 
        where
            member0_.id=?
            
name = 회원1, age = 31

실행된 SQL

SELECT m.* FROM Member m WHERE m.id = ?

외래 키 값#

외래 키 값은

Member.java

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "TEAM_ID")   // ** 연관관계로 매핑된 외래키
    private Team team;

엔티티를 파라미터로 전달

Team team = em.find(Team.class, 1L);

String jpql = "SELECT m FROM Member m WHERE m.team = :team";

List resultList = em.createQury(jpql)
                    .setParameter("team", team)
                    .getResultList();

JpqlMain.java

            Team team1 = new Team();
            team1.setName("팀A");
            em.persist(team1);

            Team team2 = new Team();
            team2.setName("팀B");
            em.persist(team2);

            Team team3 = new Team();
            team3.setName("팀C");
            em.persist(team3);

            Member member1 = new Member();
            member1.setUsername("회원1");
            member1.setAge(31);
            member1.changeTeam(team1);
            member1.setType(MemberType.USER);
            em.persist(member1);

            Member member2 = new Member();
            member2.setUsername("회원2");
            member2.setAge(32);
            member2.changeTeam(team1);
            member2.setType(MemberType.USER);
            em.persist(member2);

            Member member3 = new Member();
            member3.setUsername("회원3");
            member3.setAge(33);
            member3.changeTeam(team2);
            member3.setType(MemberType.USER);
            em.persist(member3);

            Member member4 = new Member();
            member4.setUsername("회원4");
            member4.setAge(34);
            member4.changeTeam(team3);
            member4.setType(MemberType.USER);
            em.persist(member4);

            em.flush();
            em.clear();

            String sQuery = "SELECT m FROM Member m WHERE m.team = :team";

            List<Member> resultList = em.createQuery(sQuery, Member.class)
                    .setParameter("team",team1)
                    .getResultList();


            for(Member member : resultList){
                System.out.println("name = " + member.getUsername()+ ", age = " + member.getAge());
            }

            tx.commit();

console

Hibernate: 
    /* SELECT
        m 
    FROM
        Member m 
    WHERE
        m.team = :team */ select
            member0_.id as id1_0_,
            member0_.age as age2_0_,
            member0_.TEAM_ID as team_id5_0_,
            member0_.type as type3_0_,
            member0_.username as username4_0_ 
        from
            Member member0_ 
        where
            member0_.TEAM_ID=?
            
name = 회원1, age = 31
name = 회원2, age = 32

식별자를 직접 전달

Team team = em.find(Team.class, 1L);

String jpql = "SELECT m FROM Member m WHERE m.team.id = :teamId";

List resultList = em.createQury(jpql)
                    .setParameter("teamId", teamId)
                    .getResultList();

JpqlMain.java

            Team team1 = new Team();
            team1.setName("팀A");
            em.persist(team1);

            Team team2 = new Team();
            team2.setName("팀B");
            em.persist(team2);

            Team team3 = new Team();
            team3.setName("팀C");
            em.persist(team3);

            Member member1 = new Member();
            member1.setUsername("회원1");
            member1.setAge(31);
            member1.changeTeam(team1);
            member1.setType(MemberType.USER);
            em.persist(member1);

            Member member2 = new Member();
            member2.setUsername("회원2");
            member2.setAge(32);
            member2.changeTeam(team1);
            member2.setType(MemberType.USER);
            em.persist(member2);

            Member member3 = new Member();
            member3.setUsername("회원3");
            member3.setAge(33);
            member3.changeTeam(team2);
            member3.setType(MemberType.USER);
            em.persist(member3);

            Member member4 = new Member();
            member4.setUsername("회원4");
            member4.setAge(34);
            member4.changeTeam(team3);
            member4.setType(MemberType.USER);
            em.persist(member4);

            em.flush();
            em.clear();

            String sQuery = "SELECT m FROM Member m WHERE m.team.id = :teamId";

            List<Member> resultList = em.createQuery(sQuery, Member.class)
                    .setParameter("teamId",team1.getId())
                    .getResultList();


            for(Member member : resultList){
                System.out.println("name = " + member.getUsername()+ ", age = " + member.getAge());
            }

            tx.commit();

console

Hibernate: 
    /* SELECT
        m 
    FROM
        Member m 
    WHERE
        m.team.id = :teamId */ select
            member0_.id as id1_0_,
            member0_.age as age2_0_,
            member0_.TEAM_ID as team_id5_0_,
            member0_.type as type3_0_,
            member0_.username as username4_0_ 
        from
            Member member0_ 
        where
            member0_.TEAM_ID=?
            
name = 회원1, age = 31
name = 회원2, age = 32

실행된 SQL

SELECT m.* FROM Member m WHERE m.team_id = ? 

이전 소스#

src/main/java/jpql/domain/Member.java

package jpql.domain;

import javax.persistence.*;


@Entity
public class Member {

    public Member(){
    }

    @Id @GeneratedValue
    private Long id;

    private String username;

    private int age;

    @ManyToOne
    @JoinColumn(name = "TEAM_ID")
    private Team team = new Team();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public jpql.domain.Team getTeam() {
        return team;
    }

    public void setTeam(jpql.domain.Team team) {
        this.team = team;
    }
    
    @Override
    public String toString() {
        return "Member{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", age=" + age +
                '}';
    }
}

src/main/java/jpql/domain/Team.java

package jpql.domain;

import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;


@Entity
public class Team {

    public Team() {
    }

    @Id @GeneratedValue
    private Long id;

    private String name;

    @OneToMany(mappedBy = "team")
    private List<Member> members = new ArrayList<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Member> getMembers() {
        return members;
    }

    public void setMembers(List<Member> members) {
        this.members = members;
    }
    
    @Override
    public String toString() {
        return "Team{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

src/main/java/jpql/domain/Order.java

package jpql.domain;

import javax.persistence.*;

@Entity
@Table(name = "ORDERS") //ORDER 가 예약어라 ORDERS로 테이블 명칭 지정
public class Order {
    public Order() {
    }

    @Id @GeneratedValue
    private Long id;

    private int orderAmount;

    @Embedded
    private Address orderAddress;

    @ManyToOne
    @JoinColumn(name = "PRODUCT_ID")
    private Product product;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public int getOrderAmount() {
        return orderAmount;
    }

    public void setOrderAmount(int orderAmount) {
        this.orderAmount = orderAmount;
    }

    public Address getOrderAddress() {
        return orderAddress;
    }

    public void setOrderAddress(Address orderAddress) {
        this.orderAddress = orderAddress;
    }

    public Product getProduct() {
        return product;
    }

    public void setProduct(Product product) {
        this.product = product;
    }
}

src/main/java/jpql/domain/Address.java

package jpql.domain;

import javax.persistence.Embeddable;
import java.util.Objects;

@Embeddable
public class Address {
    private String city;
    private String street;
    private String zipcode;

    public String getCity() {
        return city;
    }

    private void setCity(String city) {
        this.city = city;
    }

    public String getStreet() {
        return street;
    }

    private void setStreet(String street) {
        this.street = street;
    }

    public String getZipcode() {
        return zipcode;
    }

    private void setZipcode(String zipcode) {
        this.zipcode = zipcode;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Address)) return false;
        Address address = (Address) o;
        return Objects.equals(getCity(), address.getCity()) && Objects.equals(getStreet(), address.getStreet()) && Objects.equals(getZipcode(), address.getZipcode());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getCity(), getStreet(), getZipcode());
    }

}

src/main/java/jpql/domain/Product.java

package jpql.domain;

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

@Entity
public class Product {
    public Product() {
    }

    @Id @GeneratedValue
    private Long id;

    private String name;

    private int price;

    private int stockAmount;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    public int getStockAmount() {
        return stockAmount;
    }

    public void setStockAmount(int stockAmount) {
        this.stockAmount = stockAmount;
    }
} 	

src/main/java/jpql/JpqlMain.java

package jpql;

import jpql.domain.*;

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

public class JpqlMain {
    //psvm 단축키로 생성 가능
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpql");
        EntityManager em = emf.createEntityManager();
        EntityTransaction tx = em.getTransaction();

        tx.begin(); // [트랜잭션] 시작

        try{
		

        }catch (Exception e){
            e.printStackTrace();
            tx.rollback();
        }finally {
            em.close();
        }
        emf.close();
    }

}

참고#

• 자바 ORM 표준 JPA - 김영한