JPA의 페이징과 정렬

1. JPA 의 페이징

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• JPA에서 페이징 하는 방법
• 조건
  • 검색 조건 : 나이 10살
  • 정렬 조건 : 이름으로 내림차순
  • 페이징 조건 : 첫 번째 페이지, 페이지 당 보여 줄 데이터는 3건

 

 

2. 예제

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• setFirstResult() : 몇 번 째 부터?
• setMaxResult() : 몇 개?

  public List<Member> findbyPage(int age, int offset, int limit){
        return em.createQuery("select m from Member m where m.age = :age order by m.userName desc")
                .setParameter("age", age)
                .setFirstResult(offset) //몇 번째부터?
                .setMaxResults(limit) // 몇 개?
                .getResultList();
    }

    /**
     * total count가져오기.
     */
    public long totalCount(int age){
        return em.createQuery("select count(m) from Member m where m.age = :age", Long.class)
                .setParameter("age", age)
                .getSingleResult();
    }

    @Test
    public void paging(){
        //given
        memberJpaRepository.save(new Member("member1", 10));
        memberJpaRepository.save(new Member("member2", 10));
        memberJpaRepository.save(new Member("member3", 10));
        memberJpaRepository.save(new Member("member4", 10));
        memberJpaRepository.save(new Member("member5", 10));

        int age = 10;
        int offset =0;
        int limit = 3;
        //when
        List<Member> members = memberJpaRepository.findbyPage(age, offset, limit);
        long totalCount = memberJpaRepository.totalCount(age);

        //then
        Assertions.assertThat(members.size()).isEqualTo(3);
        Assertions.assertThat(totalCount).isEqualTo(5);
    }

    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_.age=? 
    order by
        member0_.user_name desc limit ?
        
        
        
    select
        count(member0_.member_id) as col_0_0_ 
    from
        member member0_ 
    where
        member0_.age=?

 

 

3.GitHub : 210829 JPA, Paging

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GitHub - bsh6463/SpringDataJpa