关系数据库中一种混合类不完全信息的引入

本文介绍了关系数据库中信息不完全性的含义及其表现，论述了关系数据库中不同范畴不完全性同时存在的可能性和必然性，并在关系模式中引入一种混合类不完全信息。为了能够表示和处理关系数据库中这种混合类不完全信息，文中最后给出了一种简化的扩展关系模型。

in this paper, the meaning and expression of incompleteness of information in relational database are presented, and the possibility and necessity that incompleteness in different category exists simultaneously in relational database are discussed. One kind of mixed-type incomplete information is led into relational model. In order to express and process mixed-type incomplete information in relational database, a- simplified expanded relational model is given.