摘要
关系代数是关系数据库的理论推演代数基础,而SQL是具体实现的标准计算机语言,特别是关系代数之中的除问题,很多情况下仅仅是理论抽象代数形式。本文通过对关系代数的深入剖析,分解为近似除和关系整除,通过实际案例进行关系代数除运算比较和推演,并最终通过SQL实现。
Relational algebra is based on relational database theory, SQL is a concrete realization of the standard computer lan- guage. Particularly, the division problem in relational algebra, that＇ s only the abstract theory problems. This paper analyzes rela- tional algebra in depth, and that is devided two parts： approximate divide and exact relation division. The paper achieves SQL in approximate divide and exact relation division by relational algebra.
出处
《计算机与现代化》
2010年第4期54-56,共3页
Computer and Modernization
关键词
关系代数
SQL
除
relational algebra
SQL
division
