基本上，我试图弄清楚亚马逊如何构建他们的图书部分。查看亚马逊的书页（https://www.amazon.com/s/ref=lp_2_ex_n_1?rh=n%3A283155&bbn=283155&ie=UTF8&qid=1522817105）。
我们有几个主要类别：Arts＆amp;摄影，传记＆amp;回忆录等。
如果我点击传记＆amp;回忆录，例如，我导致了一系列子类别。 I.E.传记与传记回忆录＆gt;历史＆gt;亚洲＆gt;日本
例如，有重复的子类别名称：历史＆gt;亚洲＆gt;日本
如何映射此类信息以使其可扩展？
以下是错误的方法......？
Categories table
+----+-----------------------+-----------+
| id | name | parent_id |
+----+-----------------------+-----------+
| 1 | Biographies & Memoirs | null |
| 2 | Historical | 1 |
| 3 | Asia | 2 |
| 4 | History | null |
| 5 | Asia | 4 |
| 6 | Japan | 5 |
| 7 | Japan | 3 |
+----+-----------------------+-----------+
Books
+----+-------------------------------------+----------+
| id | name | category |
+----+-------------------------------------+----------+
| 1 | The Lone Samurai | 7 |
| 2 | The Human Tradition in Modern Japan | 7 |
| 3 | Okinawa: The Last Battle | 6 |
+----+-------------------------------------+----------+
Authors
+----+---------------+----------+
| id | firstname | lastname |
+----+---------------+----------+
| 1 | James M. | Burns |
| 2 | Roy E. | Appleman |
| 3 | Russell A. | Gugeler |
| 4 | John | Stevens |
| 5 | William Scott | Wilson |
| 6 | Anne | Walthall |
+----+---------------+----------+
Authors to books (Many to many)
+---------+-----------+
| book_id | author_id |
+---------+-----------+
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
| 3 | 4 |
| 1 | 5 |
| 2 | 6 |
+---------+-----------+