非确定性数据库中空值处理

尽管关系数据库有很多优势,但它缺乏一种处理非确定性数据的能力.目前,已经提出了几种将非确定性结合到关系数据库模型的方法,它们对关系数据库模型做了诸多扩展.但空值问题依旧存在,一些模型根本就没有考虑空值因素.这违背了非确定性数据库要更加真实地反应现实世界的初衷.为此,给出了一种非确定性数据库系统中空值处理方法,改进现有非确定性数据库模型中对空值处理不完善的情况.

On handling NULL values in uncertain database

Although the relational databases have a wide range of advantages,it lacks a way to handle uncertain data.Several methods have been proposed for incorporating uncertain data into relational databases and extended the relational databases model in some aspect.However,most of them lack a way to handle NULL value.In some model,NULL value is ignored.These violate a rule that uncertain database will reflect the real world as well as possible.A method of handling NULL value in uncertain database systems was put f...