数据库模式分解为满足P_3及无α环的条件  

THE CONDITION UNDER WHICH A DATABASE SCHEMA CAN BE DECOMPOSED INTO ONE MEETING P 3 AND WITHOUT α CYCLE

作　　者：郝忠孝[1] 迟乐军[1] 管伟光 张晓冬 

机构地区：[1]哈尔滨工业大学

出　　处：《计算机研究与发展》1999年第1期101-105,共5页Journal of Computer Research and Development

基　　金：黑龙江省自然科学基金

摘　　要：文中讨论了当某一个属于ＦＤ集Ｆ的最小归并依赖集具有某些性质时，属于ＦＤ集Ｆ的任意最小归并依赖集同样具有相同性质；还给出了广义左部冲突、广义右部冲突等概念．在此基础上给出并证明了无内部冲突的数据库模式分解为满足Ｐ３及无α环性质的充要条件。That any minimum merge dependency set belonging to the set of FD F has the same properties when some minimum merge dependency set belonging to the set of FD F has some properties is discussed.And then the concepts of generalized left side conflict and generalized right conflict of the set of FD F are given.The full and necessary condition under which a database schema without inside conflict can be decomposed into one meeting P 3 and without α cycle, and the necessary condition under which a database schema with inside conflict can be decomposed into one meeting P 3 and without α cycle are given and proved.

关 键 词：内部冲突 无Α环 模式分解 数据库模式 

分 类 号：TP311.13[自动化与计算机技术—计算机软件与理论]