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                ## **1、簡述關系數據庫中表與表的 3 種關系** **1)一對一的關系 例如:** 一個人對應一個唯一的身份證號,即為一對一的關系。 **2)一對多關系 例如:** 一個班級對應多名學生,一個學生只能屬于一個班級,即為一對多關系 **3)多對多關系 例如:** 一個學生可以選多門課程,而同一門課程可以被多個學生選修,彼此的對應關系 即是多對多關系 ## **2、一對一的關系** ![](https://box.kancloud.cn/740e1a9a544ede383ee721905fc203bc_825x626.png) ## **3、一對多的關系** ![](https://box.kancloud.cn/f571623eb504cb3c00a403199faa5a44_655x359.png) ![](https://box.kancloud.cn/b74139aaf2a48edcffcd0f9b3fecd072_606x428.png) ![](https://box.kancloud.cn/21fbb0a20583ed73fb9235bbcff827c6_1374x304.png) ## **4、多對多的關系** ![](https://box.kancloud.cn/141e24f88a734901bad72272a42bdda7_884x377.png) ![](https://box.kancloud.cn/1b2566702446c5a6d8e5c91aa6dec532_1152x616.png)
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