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求关系模式全部候选关键字的算法
引用本文:郝忠孝,刘国华.求关系模式全部候选关键字的算法[J].计算机学报,1991(4).
作者姓名:郝忠孝  刘国华
作者单位:东北重型机械学院,东北重型机械学院 富拉尔基 161024,富拉尔基 161024
摘    要:本文利用对属性进行分类的方法研究了一个属性成为主属性应该满足的条件.着重讨论了当一个属性既出现于函数依赖的左部,又出现于函数依赖的右部时成为主属性的必要条件和充分条件.并在此基础上,提出了一个求关系模式全部候选关键字的有效、易行算法.

关 键 词:关系模式  候选关键字  左元属性  右元属性  双元属性

AN ALGORITHM TO FIND OUT ALL CANDIDATE KEYS OF RELATION SCHEMA
Hao Zhongxiao and Liu Guohua.AN ALGORITHM TO FIND OUT ALL CANDIDATE KEYS OF RELATION SCHEMA[J].Chinese Journal of Computers,1991(4).
Authors:Hao Zhongxiao and Liu Guohua
Abstract:The condition that an attribute being a Primary Attribute is studied by classifying the attributes. The essential and full condition that an attribute being a primary Attribute when it appears in both the left and the right of Functional Dependencies are discussed. An algorithm to find out all Candidate key of Relation Schema is proposed.
Keywords:Relation schema  candidate keys  left hand meta attribute  right hand meta Attribute  both hands meta attribute  
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