상품 엔티티 개발(비즈니스 로직 추가) @Entity@Inheritance(strategy = InheritanceType.SINGLE_TABLE)@DiscriminatorColumn(name = "dtype")@Getter @Setterpublic class Item { @Id @GeneratedValue @Column(name = "item_id") private Long id; private String name; private int price; private int stockQuantity; @ManyToMany(mappedBy = "items") private List categories = new ArrayList(); //==비즈니스 로..