Backend/JPA2025. 4. 19. 12:52@ManyToOne의 Optional 속성에 따라 변경되는 JOIN 방식 (LEFT JOIN vs INNER JOIN)
1. 상황과 문제점예시 Entitypublic class CategoryEntity extends BaseEntity { ... @Column(name = "name", nullable = false, length = 20) private String name; ... @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "parent_id") private CategoryEntity parentCategoryEntity; ...}예시 쿼리 메소드public interface CategoryJpaRepository extends JpaRepository { boolean existsByParentCategoryEn..