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1、貞TH二銭左巒信息与电气工程学1»<30.ORXNFQimfllTiaNSrBLECT1K亿eNflXNEEHDaHEBffU英文参考文献原文复印件及译文专业：计算机科学与技术姓名：张洪源学号：110210121指导教师：孙胜娟完成日期2015年6月英文原文DatabaseModelIntroductionW.JasonGilmoreAdatabase(sometimesspelleddatabase)isalsocalledanelectronicdatabase,referringtoanycollectionofda
2、taorinformation,andthatisspeciallyorganizedforrapidsearchandretrievalbyacomputer.Databasesarestructuredtofacilitatethestorage,retrieval,modification,anddeletionofdatainconjunctionwithvariousdata-processingoperations.Databasescanbestoredonmagneticdiskortape,optical
3、disk,orsomeothersecondarystoragedevice.Adatabaseconsistsofafileorasetoffiles.Theinformationinthesefilesmaybebrokendownintorecords,eachofwhichconsistsofoneormorefields.Fieldsarethebasicunitsofdatastorage,andeachfieldtypicallycontainsinformationpertainingtooneaspect
4、orattributeoftheentitydescribedbythedatabase.Usingkeywordsandvarioussortingcommands,userscanrapidlysearch,rearrange,group,andselectthefieldsinmanyrecordstoretrieveorcreatereportsonparticularaggregateofdata.Complexdatarelationshipsandlinkagesmaybefoundinallbutthesi
5、mplestdatabases.Thesystemsoftwarepackagethathandlesthedifficulttasksassociatedwithcreating,accessing,andmaintainingdatabaserecordsiscalledadatabasemanagementsystem(DBMS).TheprogramsinaDBMSpackageestablishaninterfacebetweenthedatabaseitselfandtheusersofthedatabase.
6、(Theseusersmaybeapplicationsprogrammers,managersandotherswithinformationneeds,andvariousOSprograms)ADBMScanorganize,process,andpresentselecteddataelementsformthedatabase.Thiscapabilityenablesdecisionmakerstosearch,probe,andquerydatabasecontentsinordertoextractansw
7、erstononrecurringandunplannedquestionsthataren'tavailableinregularreports.Thesequestionsmightinitiallybevagueand/orpoorlydefined,butpeoplecan“browse”throughthedatabaseuntiltheyhavetheneededinformation.Inshort,theDBMSwill“manage"thestoreddataitemsandassembletheneed
8、editemsfromthecommondatabaseinresponsetothequeriesofthosewhoaren?tprogrammers.Adatabasemanagementsystem(DBMS)iscomposedofthreemajorparts:(1)astoragesubs
