페치 조인

@Test
void 사용자를_조회하며_연관된_팀을_함께_조회() {
    em.flush();
    em.clear();

    String jpql = "select u from User u join fetch u.team";

    em.createQuery(jpql, User.class).getResultList();
}

Hibernate: 
select u.user_id, u.team_id, u.username, t.teamname 
from user u inner join team t 
on u.team_id=t.team_id

컬렉션 페치조인의 뻥튀기

@Test
void 팀을조회하는데_users를_페치조인(){
    em.flush();
    em.clear();

    String jpql = "select t from Team t join fetch t.users";

    List<Team> resultList = em.createQuery(jpql, Team.class).getResultList();
    for (Team team : resultList) {
        System.out.println("team = " + team.getName() + " teamSize = " + team.getUsers().size());
    }
}

Hibernate: 
select t.team_id, t.teamname, u.team_id, u.username, team_id, user_id 
from team t inner join user u
on team0_.team_id=users1_.team_id

team = 떡잎마을 방범대 teamSize = 2
team = 떡잎마을 방범대 teamSize = 2