```java public class Category { @ManyToMany(targetEntity = Book.class, fetch = FetchType.EAGER) @JoinTable( //多對多查詢將會添加一張中間表，該中間表SpringDataJpa會自動創建 name = "book_category_middle", //category_id 對應 Category.id 屬性名，將會在中間表中存儲 category_id 物理外鍵 joinColumns = {@JoinColumn(name = "category_id", referencedColumnName = "id")}, //book_id 對應 Book.id 屬性名，將會在中間表中存儲 book_id 物理外鍵 inverseJoinColumns = {@JoinColumn(name = "book_id", referencedColumnName = "id")} ) private List<Book> bookList; } ``` ```java public class Book { //bookList 對應 Category.bookList 屬性名 @ManyToMany(mappedBy = "bookList", fetch = FetchType.EAGER) private List<Category> categoryList; } ``` >[warning] 如果你使用 lombok 請查看章節【注意事項】，了解一些細節。