Querydsl vs JPQL

1. JPQL

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• 문자로 작성됨 -> 오타나면 실행해봐야 알 수 있음.

    @Test
    public void startJPQL(){
        //member1 찾기
        String qlString  = "select m from Member m where m.username = :username";

        Member findMember = em.createQuery(qlString, Member.class)
                .setParameter("username", "member1")
                .getSingleResult();

        assertThat(findMember.getUsername()).isEqualTo("member1");
    }

 

 

 

2.Querydsl

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• JPAQueryFactory에 entityManger 넘겨줌
• QMember생성시 변수 명에 별칭 지정. -> 잘 안씀
• .setParameter() 필요 없음-> prepare statement binding 방식?
• -->parameter binding 자동으로 함.
• 자바 코드로 작성하기 때문에 컴파일 단계에서 오류 잡을 수 있음.

    @Test
    public void startQuerydsl(){
        JPAQueryFactory queryFactory = new JPAQueryFactory(em);
        //변수명에 별칭 지정. 사실 크게 중요하지 않음 ㅋㅋ 안씀 ㅋㅋㅋ
        QMember m = new QMember("m"); //어떤 QMember인지 구분

        Member findMember = queryFactory
                .select(m)
                .from(m)
                .where(m.username.eq("member1"))
                .fetchOne();

        assertThat(findMember.getUsername()).isEqualTo("member1");

    }

    select
        member0_.member_id as member_i1_1_,
        member0_.age as age2_1_,
        member0_.team_id as team_id4_1_,
        member0_.username as username3_1_ 
    from
        member member0_ 
    where
        member0_.username=?

 

 

 

3. JPAQueryFactory를 필드로

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• 필드로 빼서 사용이 가능

@SpringBootTest
@Transactional
public class QuerydslBasicTest {

    @Autowired
    EntityManager em;

    JPAQueryFactory queryFactory;


    @BeforeEach
    public void before(){
        queryFactory = new JPAQueryFactory(em);

 

 

4.GitHub : 210901 JPQL VS Querydsl

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GitHub - bsh6463/Querydsl