6. @Query - 엔티티, 값, DTO 조회하기

1) 엔티티 조회

select m

public interface MemberRepository extends JpaRepository<Member, Long>{

    @Query("select m from Member m where m.username = :username and m.age = :age")
    List<Member> findUser(@Param("username") String username, @Param("age") int age);
}

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2) 값 조회

select m.username

JPA 값 타입(@Embedded)도 이 방식으로 조회

public interface MemberRepository extends JpaRepository<Member, Long>{

    @Query("select m.username from Member m")
    List<String> findUsernameList();
}

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3) DTO 조회

select new [패키지명경로.DTO명]()

🚨주의🚨
패키지 경로 모두 작성!!

public interface MemberRepository extends JpaRepository<Member, Long>{

	@Query("select new study.datajpa.dto.MemberDto(m.id, m.username, t.name) from Member m join m.team t")
    List<MemberDto> findMemberDto();
}

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출처

김영한 강사님 - 인프런 실전! 스프링 데이터 JPA