华南农业大学数据库考试答案

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1、华南农业大学期末考试试卷（A卷）2015-2016学年第一学期考试科目：数据库系统考试类型：闭卷考试时间：120分钟学号姓名年级专业装题号一二三四五总分得分评阅人订Question1:true-falsequestion(30points)Foreachofthefollowingstatements,indicatewhetheritisTRUEorFALSE(UsingTforTRUE得分andFforFALSE).Youwillget1pointforeachcorrectanswer,and0pointforeachwrongorblankanswer

2、.BESURETOWRITEYOURANSWERINTHEANSWERSHEET!线1.Databasesystemsaredesignedforbothdefiningstoragestructuresandprovidingmechanismsformanipulationofinformation.2.Comparingwithdatabasesystem,file-processingsystemhasmanydisadvantagessuchlikedataredundancyandconsistency,concurrent-accessanoma

3、lies.3.Physicaldataindependenceindatabasemeansthattheuserworkingonthelogicallevelneedknownothingaboutcomplexityofthephysicallevelofdatabase.4.Theoveralldesignofdatabaseisthedatabaseschema,whilecollectionofdatastoredinthedatabaseataparticularmomentisaninstanceofthedatabase.5.TheEntit

4、y-Relationshipdatamodelisoftenusedinlogical1designphase.6.SQLisarelationallanguagethatusedasbothDDLandDML.7.Metadataisdataaboutdatathatarestoredindatadictionary.8.Atupleisalsoknownasacolumnindatabasetable.9.ArelationshipinanERmodelcanhasitsownattributes.10.Compositeattributesarenota

5、llowedinERmodel.11.Theclosureofafunctionaldependencysetincludesallfunctionaldependenciesintheset.12.Dependencypreservationisnecessarytoapracticaldecompositionalgorithm.13.Themostcommontypeofrelationshipencounteredindatamodelingisternaryrelationship.14.ArelationalschemaRisinBCNFifdom

6、ainsofallattributesofRareatomic.15.Atuplevariableisavariablethatstandsforatuple,inotherwords,itisavariablewhosedomainisthesetofalltuples.16.Aforeignkeyofarelationisasetofattributes(oneormore)thatallowustoidentifyatupleinthatrelationuniquely.17.Thesetintersectionoperationcanbereplaci

7、ngbyapairofset-differenceoperations.18.Anyrelationthatisnotpartofthelogicalmodel,butismade2visibletoauserasavirtualrelation,iscalledaview.19.InSQL,theouterjoinoperationdefineshowtuplesineachrelationthatdonotmatchanytupleintheotherrelationare装treated.20.Themaindatabasedesignphaseincl

8、udesrequirementanal