1. EAGER vs LAZY
1. DTO가 아닌 Entity에 List<Reply>
2. EAGER
3. LAZY
4. 최종
select b from Board b join fetch b.user left join fetch b.replies where b.id = :id
2. reply까지 join
select b from Board b join fetch b.user left join fetch b.replies r join fetch r.user where b.id = :id
3. 서버 실행 후 게시글 상세보기 화면을 들어가면