摘要
本文从关系代数的运算和数据操作出发 ,给出了常见的关系代数表达式的基本要素、基本构造类型和 SQL语言编程指导原则 ,进而用
This article, based on the operation of relational algebra and data manipulation, presents basic elements of conventional relational algebra expression, basic structural types and principle governing SQL programming. It also introduces how to carry out relational data manipulation with the help of data inquiry function.
