并:
差:
笛卡兒積:
投影:
選擇:
交:
聯(lián)接:
除:
例題:
參考連接:
https://blog.csdn.net/qq_37521566/article/details/80854134
https://blog.csdn.net/qq_39368007/article/details/86586563
元組演算
例題:
? ?參考連接:
????????????https://blog.csdn.net/xqf309/article/details/8865269
參考連接:
https://blog.csdn.net/qq_37521566/article/details/80854134
https://blog.csdn.net/qq_39368007/article/details/86586563
? ?參考連接:
????????????https://blog.csdn.net/xqf309/article/details/8865269