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1、1000-9825/2003/14(02)0247©2003JournalofSoftware软件学报Vol.14,No.2∗具有全序时态类型集时态函数依赖集的研究1,2+1,2,3姚春龙,郝忠孝1(哈尔滨工业大学计算机科学与工程系,黑龙江哈尔滨150001)2(齐齐哈尔大学计算机科学与技术系,黑龙江齐齐哈尔161006)3(哈尔滨理工大学计算机与控制学院,黑龙江哈尔滨150080)StudyonSetofTemporalFunctionalDependencieswithTotallyOrderedSetofTemporalType
2、s1,2+1,2,3YAOChun-Long,HAOZhong-Xiao1(DepartmentofComputerScienceandEngineering,HarbinInstituteofTechnology,Harbin150001,China)2(DepartmentofComputerScienceandTechnology,QiqihrUniversity,Qiqihar161006,China)3(SchoolofComputerandControl,HarbinUniversityofScienceandTechno
3、logy,Harbin150080,China)+Correspondingauthor:Phn:86-452-2738171,Fax:86-452-2725454,E-mail:yclhw@263.nethttp://www.hit.edu.cnReceived2001-07-28;Accepted2001-11-05YaoCL,HaoZX.Studyonsetoftemporalfunctionaldependencieswithtotallyorderedsetoftemporaltypes.JournalofSoftware,
4、2003,14(2):247~252.Abstract:Thepurposeofgooddatabaselogicaldesignistoeliminatedataredundancyandinsertion,deletionandupdateanomalies.Fortemporaldatabases,temporalschemesmaybenormalizedbyusingconstraintsoftemporalfunctionaldependencies(TFDs)withmultipletemporalgranulariti
5、es.However,theadoptionoftemporaldimensionandusageofmultipletemporalgranularitiesmakeitverycomplicatedtodesignatemporaldatabase.Generally,thesetoftemporaltypesthatcanbeprocessedbyasystemandinvolvedinlotsofapplications,meettotallyorderedrelation,andthesetofTFDswithatotall
6、yorderedsetoftemporaltypesiscloselyrelatedtotheArmstrongaxiomsoftraditionalfunctionaldependencies(FDs).ByanalyzingtheexistingrelationshipsbetweenTFDsandFDsandutilizingcorrespondingalgorithmsfortraditionalsetofFDs,someimportantalgorithmssuchasmembershipandfiniteclosureof
7、attributesalgorithmsareproposedforgivensetofTFDs.Thesealgorithmsarethebasisoffurthernormalizationfortemporaldatabases.Keywords:temporaldatabase;functionaldependency(FD);normalization;relationalscheme;logicaldesign;logicalimplication摘要:好的数据库逻辑设计目标是消除数据冗余以及插入、删除和更新异常.对于时态
8、数据库,可以通过具有多时间粒度的时态函数依赖(TFDs)约束对时态数模式进行规范化.但是由于时间维的引入和多时间粒度的使∗SupportedbytheNaturalScienceFoundationofHeilongji
