
并:

差:


笛卡儿积:


投影:


选择:


交:


联接:


除:



例题:




参考连接:
https://blog.csdn.net/qq_37521566/article/details/80854134
https://blog.csdn.net/qq_39368007/article/details/86586563
元组演算



例题:








参考连接:
https://blog.csdn.net/xqf309/article/details/8865269
参考连接:
https://blog.csdn.net/qq_37521566/article/details/80854134
https://blog.csdn.net/qq_39368007/article/details/86586563
参考连接:
https://blog.csdn.net/xqf309/article/details/8865269