关系数据库设计过程冗余模式消除方法

THE METHOD OF REMOVING THE REDUNDANT SCHEME IN THE PEOCESS OF RELATIONAL DATABASE DESIGN

消除冗余模式是数据库设计中应考虑的重要问题之一.本文首先把不同冗余程度的冗余模式分为三级,即绝对冗余模式、相对冗余模式和函数依赖冗余模式,并作了形式化描述;然后,讨论了冗余模式的性质,并给出了消除各种冗会模式的方法,这些方法本质是多项式时间复杂度的.

Removing the redundant scheme is the one of important problems that must bethought in database design. In this paper,we firstdivide the redundant shemes in its lev-el of redundancy into threedegrees of redundant schemes: absolute redundant scheme,relativeredundant scheme and functional dependenceis redundant scheme, anddescrib itmathmatically. We second discuss the properties of theredundant scheme,and give meth-ods of removing all of redundant schemes with the complexity of tec methods essentiallybeing polynomial.