数据约束表达研究——比较条件函数依赖与传统函数依赖

在信息系统的范畴内,数据约束不同于业务流程和数据流程,数据约束是数据应遵循的语义限制,反映应用领域的信息规则,对数据约束的形式化表达是设计和管理数据库系统的基本任务.为了探讨数据约束的形式化表达问题,对条件函数依赖和传统函数依赖这两种数据约束表达方法作了比较研究.通过比较分析两者的表达能力、表达形式、对数据约束规律的揭示以及应用范围,指出了数据约束表达的三个层次.研究对数据库系统的设计与管理有理论参考价值.

Comparative Research on Conditional Functional Dependency and Traditional Functional Dependency

In the context of information systems,data constraint is different from the business process and data flow.Data restraints are the semantic restrictions data should follow,reflecting the information rules of the application.The formal expression of data constraints is basic tasks to design and manage the database system.In order to discuss the problems of the formal expression of data constraints,two expression methods of data constraints,the conditional functional dependency and traditional functional dependency,are compared.On the basis of contrasting expressive capability,expressive forms,the revealing discipline of data constraints and the application scopes,indicates the three levels of a data constraint expression.This research has theoretical reference values on database system design and management.