쿼리 메서드

1. Query Method의 기능

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• 메소드 이름으로 쿼리 생성
• NamedQuery
• @Query - 리파지토리 메소드에 쿼리 정의
• 파라미터 바인딩
• 반환 타입
• 페이징과 정렬
• 벌크성 수정 쿼리
• @EntityGraph

 

2. 메소드 이름으로 쿼리 생성

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• 메소드 이름을 분석해서 JPQL 쿼리 실행
• 이름과 나이를 기준으로 회원을 조회하려면?
• 먼저 JPA로 짜보자

 public List<Member> findMemberByUserNameAndAgeGreaterThan(String userName, int age){
        return em.createQuery("select m from Member m where m.userName = :userName and m.age > :age")
                .setParameter("userName", userName)
                .setParameter("age", age)
                .getResultList();
    }

 @Test
    public void findByUserNameAndAgeGreaterThan(){
        Member member1 = new Member("aaa", 10);
        Member member2 = new Member("bbb", 20);
        memberJpaRepository.save(member1);
        memberJpaRepository.save(member2);

        List<Member> findMembers = memberJpaRepository.findMemberByUserNameAndAgeGreaterThan("bbb", 10);

        Assertions.assertThat(findMembers.get(0).getUserName()).isEqualTo(member2.getUserName());
        Assertions.assertThat(findMembers.get(0).getAge()).isEqualTo(member2.getAge());
        
    }

흠 잘 된다 ㅋㅋㅋㅋ

 

근데 일일히 JPQL짜기 귀찮은데.......

 

• SpringdataJPA활용

public interface MemberRepository extends JpaRepository<Member, Long> {

    public List<Member> findMemberByUserNameAndAgeGreaterThan(String userName, int age);

}

 이렇게만 해줘도... 알아서 구현체 만들어줌... 

 @Test
    public void findByUserNameAndAgeGreaterThan(){
        Member member1 = new Member("aaa", 10);
        Member member2 = new Member("bbb", 20);
        memberRepository.save(member1);
        memberRepository.save(member2);

        List<Member> findMembers = memberRepository.findMemberByUserNameAndAgeGreaterThan("bbb", 10);

        Assertions.assertThat(findMembers.get(0).getUserName()).isEqualTo(member2.getUserName());
        Assertions.assertThat(findMembers.get(0).getAge()).isEqualTo(member2.getAge());

    }

쿼리가 날라간거도 확인 가능하다.

    select
        member0_.member_id as member_i1_0_,
        member0_.age as age2_0_,
        member0_.team_id as team_id4_0_,
        member0_.user_name as user_nam3_0_ 
    from
        member member0_ 
    where
        member0_.user_name=? 
        and member0_.age>?

 

• 쿼리 메서드 필터 조건

Spring Data JPA - Reference Documentation

 

 

 

3. 스프링 데이터 JPA가 제공하는 쿼리 메서드 기능

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• 조회: find…By ,read…By ,query…By get…By,
  
  • #repositories.query-methods.query-creation
  • 예:) findHelloBy 처럼 ...에 식별하기 위한 내용(설명)이 들어가도 된다.
  • By뒤에 조건 없으면 전체 조회
• COUNT: count…By 반환타입 long
• EXISTS: exists…By 반환타입 boolean
• 삭제: delete…By, remove…By 반환타입 long
• DISTINCT: findDistinct, findMemberDistinctBy
• LIMIT: findFirst3, findFirst, findTop, findTop3
  • #repositories.limit-query-result

Spring Data JPA - Reference Documentation

 

주의! : 엔티티의 필드명이 변경되면 인터페이스에 정의한 메서드 이름도 꼭 함께 변경해야 한다.

그렇지 않으면 애플리케이션을 시작하는 시점에 오류가 발생한다.

 

4. GitHub : 210828 QueryMethod

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GitHub - bsh6463/SpringDataJpa