基于对象时态稳定性分类特征的双时态ER模型

BITEMPORAL ENTITY-RELATIONSHIP MODEL BASED ON OBJECT TEMPORAL STABILITY CLASSIFYING FEATURE

对双时态数据库建模时以客观事物的时态特征为切入点,定义有关时态表示的双时态点、双时态组合集和双时态标签,通过分析客观对象的时态稳定性,将其划分为时态值稳定对象和时态值变对象。参照数据库概念结构设计基本方法,给出一种基于对象时态稳定性分类特征的双时态ER模型,并定义了相关的基本图元及建立规则,该模型可有效减少因模式中存在大量与时态无关属性而造成的数据冗余现象。最后给出该模型与应用较为普遍的BCDM模型相互转化的方法,使其具有推广应用价值。

When modelling the bitemporal database,temporal characters of the objective things are used as the start point,the point,combination set and label of bitemporal in regard to temporal representation are defined.By analysing the temporal stability of objective target,it is divided into temporal constant object or temporal variable object.Referring to the basic design method of database conception structure,the bitemporal entity-relationship model based on object temporal stability classifying characters is presented,moreover,the basic graphic elements and related creating rules are defined.Using this model,the data redundancy caused by abundant temporal-irrelevant attributes in the mode can be effectively reduced.Finally,the mutual conversion method of this model and the more generally used BCDM are introduced for providing it with applied value of promotion.