关系代数查询算法在Foxpro系统中的移植  

CALCULATING METHOD OF RELATIONAL ALGEBRA ON THE QUERY IS TRANSPLANTED IN FOXPRO SYSTEM

作　　者：张正玺[1] 焦占亚[1] 

机构地区：[1]陕西科技大学计算机与信息工程学院,陕西咸阳712081

出　　处：《陕西科技大学学报（自然科学版）》2003年第3期105-107,共3页Journal of Shaanxi University of Science & Technology

摘　　要：Foxpro系统基本命令集中提供有在表文件中顺序查询和索引查询的命令 ,但都是一次一记录的查询方式。Foxpro系统尽管是最小关系系统 ,但是关系代数中的投影、选择、连接、笛卡尔积和并运算都有不同程度的实现。作者在文中重点讨论了利用这些关系代数运算并借助关系代数表达式的查询算法 。Basic command set in Foxpro system gives commands on sequential query and indexical query in table files, but it queries a record at a time. Even though Foxpro system is the minimal relational system, projection, selection, join, cartesian product and union operation achieved in it in varying degrees. This article mainly discusses about the calculating method on query with the relational algebra and the expression of relational algebra. It could partially achieve to query a set at a time.

关 键 词：查询算法 FOXPRO系统 移植 索引查询 关系代数表达式 

分 类 号：G350.7[文化科学—情报学]