当前位置：网站首页>关系代数笛卡尔积和自然连接的例子
关系代数笛卡尔积和自然连接的例子
2022-06-12 12:21:00 【集电极】
笛卡尔积（Cartesian Product）又称直积，是指在数学中两个集合X和Y的一种有序对组成的集合，表示X的任何成员和Y的任何成员构成有序对。
自然连接结果基于表R和S的笛卡尔乘积,取对应的R和S中相同属性组都相同的值,同时相同属性组只保留一个
边栏推荐
- 拿来就能用的网页动画特效，不来看看？
- Google Earth engine (GEE) - quick land classification by kmeans clustering (double for loop quick parameter adjustment)
- Beyondcompare 4 uses PJ
- Open source project - (erp+ Hotel + e-commerce) background management system
- Traditional DOM rendering?
- TRON-api-波场转账查询接口-PHP版本-基于ThinkPHP5封装-附带接口文档-20220602版本-接口部署好适用于任何开发语言
- Implementation principle of kotlin extension function
- Boot entry directory
- 作物模型的区域模拟实现过程初探
- 单页面开发与多页面开发的优缺点
猜你喜欢
Point cloud registration -- GICP principle and its application in PCL
Left and right cases + rotating pictures of small dots + no time
JS attribute operation and node operation
DOM+JS+轮播图+无时间
LeetCode 497. Random points in non overlapping rectangles (prefix and + bisection)
Elk construction guide
Problems encountered in installing canvas and errors encountered in running the project
Take the web page animation effects that can be used. Don't you come and have a look?
LeetCode 890. Find and replace mode (analog + double hash table)
Performance comparison test of channel and condition variables of golang in single production and single consumption scenarios
随机推荐
Dom+js+ carousel map + no time
Autolock solves the problem of forgetting to unlock after locking
JS built in object
Google Earth engine (GEE) - quick land classification by kmeans clustering (double for loop quick parameter adjustment)
無重複字符的最長字符串（LeetCode 3）
从小白入手，从已经训练好的模型中取出weight权重参数绘制柱状图
＃ifndef＃define＃endif防止头文件重复包含， 你不是真的懂
sublime_text使用
AGCO AI frontier promotion (6.12)
回溯法, 八皇后
Backtracking, eight queens
JS pre parsing, object, new keyword
MySQL review
[译] Go语言测试进阶版建议与技巧
Conversion between ROS map picture pixels and map coordinate system coordinates
用vector保存对象时保存指针的优点, 以及reserve的使用
Macro compilation preprocessing header Win32_ LEAN_ AND_ MEAN
Imx6 uboot add lvds1 display
Automatic generation of folder directory structure
for in 与Object.keys()的区别