多时间粒度约束的时态简单范式的分解

A Deposition Algorithm on TSNF with Multigranularities Constraint

数据库逻辑设计的目的是消除数据冗余、插入和删除异常。为使时态模式满足某种范式的要求,要对时态模式进行分解,保持函数依赖和无损连接性是对算法最基本的要求。但对具有多时间粒度的时态模式进行分解时,把TBCNF作为最终目标很难实现保持函数依赖性,把T3NF作为最终目标,又很难达到规范化要求。该文提出了时态简单范式TSNF的概念及相应的分解算法,来弥补以上两点不足。

The purpose of good database logical design is to elimiate data redundancy and insertion and deletion anomalies. For a tempral model, through deposing to meet the requirements of some normal forms, in this sense, the temporal functional dependencies and the lossless deposition are the basicest aim to reach. For a temporal model with temporal multigranularities, it is difficult to depose it to TBCNF of keeping the temporal functional dependencies as well as to T3NF of satisfyinig the corresponding requirements of normal forms, So this article presents TSNF, a new kind of norlnal form, to make up for the shortcomings.