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Computer Engineering ›› 2007, Vol. 33 ›› Issue (01): 62-64. doi: 10.3969/j.issn.1000-3428.2007.01.021

• Software Technology and Database • Previous Articles     Next Articles

Deciding Problem of Database Schema Meeting Ps and α-acyclic in Functional Dependency

ZHAO Lingqiang1, GU Zhaopeng1, HAO Zhongxiao1,2,3   

  1. (1. College of Computer Science and Technology, Harbin University of Science and Technology, Harbin 150080; 2. College of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001; 3. College of Computer, Qiqihar University, Qiqihar 161006)
  • Received:1900-01-01 Revised:1900-01-01 Online:2007-01-05 Published:2007-01-05

数据库模式在FD环境下满足PS及无α环判定问题

赵龄强1,顾照鹏1,郝忠孝1,2,3   

  1. (1. 哈尔滨理工大学计算机科学与技术学院,哈尔滨 150080;2. 哈尔滨工业大学计算机科学与技术学院,哈尔滨 150001; 3. 齐齐哈尔大学计算机学院,齐齐哈尔 161006)

Abstract: By analyzing the property and characteristics of D( the minimum merge dependency set of F) when D has weak left side conflict or weak left side conflict, the notions of Ps(join-lossless, FD and SNF), condition T are introduced. On this basis, the scheme decomposition is discussed and the result concludes that when D has weak left side conflicts or weak right side conflict or doesn’t meet condition T, the decomposition meeting Ps is α-cyclic, laying the foundation for further investigation of α-acyclic decomposition.

Key words: Without inside conflict, Weak left side conflict, Weak rignt side conflict, α-acyclic, Simple normal form

摘要: 通过分析在FD集F的最小归并依赖集D存在弱左部或弱右部冲突时所具有的性质和特征,提出了PS(保持FD,无损连接且满足SNF)、条件T等概念。在此基础上讨论了数据库模式分解为SNF的无α环判定问题,给出了在D有弱左部或弱右部冲突及不满足条件T时满足PS的分解是有α环的结论,为进一步研究无α环的分解奠定了基础。

关键词: 无内部冲突, 弱左部冲突, 弱右部冲突, 无α环, 简单范式