关系代数运算与SQL查询的对应关系

CORRESPONDING RELATION OF THE RELATIONAL ALGEBRA CALCULUS AND SQL QUERY

关系代数用传统的并,差-,交,笛卡尔积和选择,投影,连接,除来表达关系操作能力,是1种抽象的查询方式,是关系数据库标准语言SQL的理论基础,与SQL的各种查询要求有一一对应关系。

Relational algebra is a kind of abstract query method. It shows relational operation function by traditional union, difference, intersection, cartesian product, selection, projection, join, derision. It is the theoretical basis of relational database standard language SQL and corresponds to each with query requirement of SQL.