关系代数中除法运算的表示

本文主要讨论了用基本运算表示除法运算的关系代数表达式。用图形法作为分析工具,给出了关系代数中除法运算的查询原理,解决了以往用抽象定义进行除法运算的难度,结合实例提出了讲授这些知识点的一些新思路和新方法,取得了较好的教学效果。

How to Express Division Operation in Relational Algebra

This article discusse smainly on the method how to express division operations with fundamental operations.It uses Graphic law as analytical tool,and gives a series of query principles of Division in Relation Algebra.It solves the problem that division operation is done by using abstract definition,and with examples,the point of such knowledge taught some new ideas and new methods,achieving better teaching results.