数据库课程设计实验报告文档格式.docx

数据库课程设计实验报告文档格式.docx

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王亮

谢明敏

学号

5040309458

班级

F0403016

F0403014

完成日期

2007/7/5

CONTENT

1.Introduction

Adatabasemanagementsystem（DBMS）iscomputersoftwaredesignedforthepurposeofmanagingdatabases.TypicalexamplesofDBMSsincludeOracle,DB2,MicrosoftAccess,MicrosoftSQLServer,Postgres,MySQLandFileMaker.DBMSsaretypicallyusedbyDatabaseadministratorsinthecreationofDatabasesystems.

ADBMSisacomplexsetofsoftwareprogramsthatcontrolstheorganization,storageandretrievalofdatainadatabase.ADBMSincludes:

1.Amodelinglanguagetodefinetheschema（relationalmodel）ofeachdatabasehostedintheDBMS,accordingtotheDBMSdatamodel.

●Thethreemostcommonorganizationsarethehierarchical,networkandrelationalmodels.Adatabasemanagementsystemmayprovideone,twoorallthreemethods.Invertedlistsandothermethodsarealsoused.Themostsuitablestructuredependsontheapplicationandonthetransactionrateandthenumberofinquiriesthatwillbemade.ThedominantmodelinusetodayistheadhoconeembeddedinSQL,acorruptionoftherelationalmodelbyviolatingseveralofitsfundamentalprinciples.ManyDBMSsalsosupporttheOpenDatabaseConnectivityAPIthatsupportsastandardwayforprogrammerstoaccesstheDBMS.

2.Datastructures（fields,recordsandfiles）optimizedtodealwithverylargeamountsofdatastoredonapermanentdatastoragedevice（whichimpliesveryslowaccesscomparedtovolatilemainmemory）.

3.Adatabasequerylanguageandreportwritertoallowuserstointeractivelyinterrogatethedatabase,analyzeitsdataandupdateitaccordingtotheusersprivilegesondata.

●Italsocontrolsthesecurityofthedatabase.

●Datasecuritypreventsunauthorizedusersfromviewingorupdatingthedatabase.Usingpasswords,usersareallowedaccesstotheentiredatabaseorsubsetsofitcalledsubschemas.Forexample,anemployeedatabasecancontainallthedataaboutanindividualemployee,butonegroupofusersmaybeauthorizedtoviewonlypayrolldata,whileothersareallowedaccesstoonlyworkhistoryandmedicaldata.

●IftheDBMSprovidesawaytointeractivelyenterandupdatethedatabase,aswellasinterrogateit,thiscapabilityallowsformanagingpersonaldatabases.However,itmaynotleaveanaudittrailofactionsorprovidethekindsofcontrolsnecessaryinamulti-userorganization.Thesecontrolsareonlyavailablewhenasetofapplicationprogramsarecustomizedforeachdataentryandupdatingfunction.

4.Atransactionmechanism,thatideallywouldguaranteetheACIDproperties,inordertoensuredataintegrity,despiteconcurrentuseraccesses（concurrencycontrol）,andfaults（faulttolerance）.

●Italsomaintainstheintegrityofthedatainthedatabase.

●TheDBMScanmaintaintheintegrityofthedatabasebynotallowingmorethanoneusertoupdatethesamerecordatthesametime.TheDBMScanhelppreventduplicaterecordsviauniqueindexconstraints;

forexample,notwocustomerswiththesamecustomernumbers（keyfields）canbeenteredintothedatabase.SeeACIDpropertiesformoreinformation（Redundancyavoidance）.

ThecomponentsofaDBMS:

TheDBMSacceptsrequestsfordatafromtheapplicationprogramandinstructstheoperatingsystemtotransfertheappropriatedata.

WhenaDBMSisused,informationsystemscanbechangedmuchmoreeasilyastheorganization'

sinformationrequirementschange.Newcategoriesofdatacanbeaddedtothedatabasewithoutdisruptiontotheexistingsystem.

OrganizationsmayuseonekindofDBMSfordailytransactionprocessingandthenmovethedetailontoanothercomputerthatusesanotherDBMSbettersuitedforrandominquiriesandanalysis.Overallsystemsdesigndecisionsareperformedbydataadministratorsandsystemsanalysts.Detaileddatabasedesignisperformedbydatabaseadministrators.

DatabaseserversarespeciallydesignedcomputersthatholdtheactualdatabasesandrunonlytheDBMSandrelatedsoftware.Databaseserversareusuallymultiprocessorcomputers,withRAIDdiskarraysusedforstablestorage.Connectedtooneormoreserversviaahigh-speedchannel,hardwaredatabaseacceleratorsarealsousedinlargevolumetransactionprocessingenvironments.

DBMS'

sarefoundattheheartofmostdatabaseapplications.SometimesDBMSsarebuiltaroundaprivatemultitaskingkernelwithbuilt-innetworkingsupportalthoughnowadaysthesefunctionsarelefttotheoperatingsystem.

FeaturesandAbilitiesofDBMS:

OnecancharacterizeaDBMSasan"

attributemanagementsystem"

whereattributesaresmallchunksofinformationthatdescribesomething.Forexample,"

color"

isanattributeofacar.Thevalueoftheattributemaybeacolorsuchas"

red"

"

blue"

silver"

etc.Latelydatabaseshavebeenmodifiedtoacceptlargeorunstructured（pre-digestedorpr