Domov technika Database management system

Database management system



Overview

Databasemanagementsystemisalarge-scalesoftwarethatmanipulatesandmanagesdatabases.Itisusedtoestablish,useandmaintaindatabases,referredtoasDBMS.Itconductsunifiedmanagementandcontrolofthedatabasetoensurethesecurityandintegrityofthedatabase.

Databasemanagementsystemisadataoperationsoftwarethatcanprovidedataentry,modification,andquery.Ithasdatadefinition,dataoperation,datastorageandmanagement,datamaintenance,communicationandotherfunctions,andcanallowmultipleuserstouse.Inaddition,thedevelopmentofdatabasemanagementsystemsiscloselyrelatedtothedevelopmentofcomputertechnology.Andinrecentyears,computernetworkshavegraduallybecomeanimportantpartofpeople'slives.Forthisreason,ifyouwanttofurtherimprovethecomputerdatabasemanagementsystem,techniciansshouldcontinuetoinnovateandreformcomputertechnology,andcontinuetobroadentheapplicationrangeofcomputerdatabasemanagementsystems,soastotrulypromotetheinnovationofcomputerdatabasemanagementsystemtechnology.

Mainfunctions

1.Datadefinition:DBMSprovidesdatadefinitionlanguageDDL(DataDefinitionLanguage)foruserstodefinethethree-levelschemastructure,two-levelimageandintegrityconstraintsofthedatabaseAndconfidentialityrestrictions.DDLismainlyusedtoestablishandmodifythedatabasestructureofthedatabase.ThelibrarystructuredescribedbyDDLonlygivestheframeworkofthedatabase,andtheframeworkinformationofthedatabaseisstoredintheDataDictionary.

2.Datamanipulation:DBMSprovidesdatamanipulationlanguageDML(DataManipulationLanguage)foruserstoimplementoperationssuchasadding,deleting,updating,andqueryingdata.

3.Databaseoperationmanagement:TheoperationmanagementfunctionofthedatabaseistheoperationcontrolandmanagementfunctionoftheDBMS,includingconcurrencycontrolinamulti-userenvironment,securitycheckandaccessrestrictioncontrol,integritycheckandTheorganizationandmanagementofexecutionandrunninglogs,transactionmanagementandautomaticrecovery,thatis,toensuretheatomicityoftransactions.Thesefunctionsensurethenormaloperationofthedatabasesystem.

4.Dataorganization,storageandmanagement:DBMSshouldorganize,storeandmanageallkindsofdata,includingdatadictionary,userdata,accesspath,etc.ItisnecessarytodeterminethefilestructureandaccessHowtoorganizethesedataatthestoragelevelandhowtorealizetheconnectionbetweenthedata.Thebasicgoalofdataorganizationandstorageistoimprovetheutilizationofstoragespace,andtoselectappropriateaccessmethodstoimproveaccessefficiency.

5.Databaseprotection:Thedatainthedatabaseisastrategicresourceoftheinformationsociety,sotheprotectionofdataisveryimportant.TheprotectionofthedatabasebytheDBMSisrealizedthroughfouraspects:databaserecovery,databaseconcurrencycontrol,databaseintegritycontrol,anddatabasesecuritycontrol.OtherprotectionfunctionsoftheDBMSincludethemanagementofsystembuffersandsomeadaptiveadjustmentmechanismsfordatastorage.

6.Databasemaintenance:Thispartincludesfunctionssuchasdataloading,conversion,dumping,reassemblyandreconstructionofthedatabase,andperformancemonitoringofthedatabase.Thesefunctionsarecompletedbyeachapplicationprogram.

7.Communication:DBMShasrelatedinterfacesforonlineprocessingwiththeoperatingsystem,time-sharingsystemandremoteoperationinput,andisresponsibleforprocessingdatatransmission.Forthedatabasesystemunderthenetworkenvironment,itshouldalsoincludethecommunicationfunctionbetweentheDBMSandothersoftwaresystemsinthenetworkandtheinteroperabilityfunctionbetweenthedatabases.

Composition

Thedatabasemanagementsystemmainlyincludes:datadefinitionlanguageandrelatedproceduresfortranslation.Withthehelpofthispart,databaseuserscanmaketheirownchoicesandcanalsoThetranslationisthusformedintoaninternalform;theprogramfordataoperationcontrol,becauseoftheworkofthisprogram,theresourcesinthedatabasecanbefullymanaged,andakindofcontrolaboutthedatacanbeachieved;theutilityprogramofthedatabasecanmakeThedatabaseisestablishedonarelativelycompletebasis,andthedatabaseismaintainedunderarelativelycompletedatabasesystem.

Accordingtofunctions,thedatabasemanagementsystemcanberoughlydividedinto6parts:

(1)Modetranslation:Providedatadefinitionlanguage(ddl).Thedatabaseschemawritteninitistranslatedintointernalrepresentation.Thelogicalstructure,integrityconstraintsandphysicalstoragestructureofthedatabasearestoredintheinternaldatadictionary.Variousdataoperationsofthedatabase(suchassearching,modifying,insertinganddeleting,etc.)andthemaintenanceandmanagementofthedatabasearebasedonthedatabasemodel.

(2)Compilationofapplicationprograms:compileapplicationprogramsthatcontainstatementstoaccessthedatabaseintotargetprogramsthatcanberununderthesupportofdbms.

(3)Interactivequery:Provideaneasy-to-useinteractivequerylanguage,suchasSQL.DBMSisresponsibleforexecutingquerycommandsanddisplayingqueryresultsonthescreen.

(4)Dataorganizationandaccess:Providethephysicalorganizationandaccessmethodofdataonperipheralstoragedevices.

(5)Transactionoperationmanagement:Providetransactionoperationmanagementandoperationlog,transactionoperationsecuritymonitoringanddataintegritycheck,transactionconcurrencycontrolandsystemrecoveryfunctions.

(6)Databasemaintenance:Providesoftwaresupportfordatabaseadministrators,includingmaintenancetoolssuchasdatasecuritycontrol,integrityassurance,databasebackup,databasereorganization,andperformancemonitoring.

Workingmode

TheworkingmodeoftheDBMSisasfollows:

(1)Acceptapplicationdatarequestsandprocessingrequests;

(2)Converttheuser’sdatarequest(high-levelinstruction)intocomplexmachinecode(low-levelinstruction);

(3)Realizetheoperationofthedatabase;

(4)FromtherightAcceptqueryresultsduringdatabaseoperations;

(5)Processthequeryresults(formatconversion);

(6)Returntheprocessingresultstotheuser.

DBMSisalwaysbasedonacertaindatamodel,soDBMScanberegardedasaspecificimplementationofacertaindatamodelonacomputersystem.Accordingtodifferentdatamodels,DBMScanbedividedintohierarchical,mesh,relational,object-oriented,etc.

Indifferentcomputersystems,duetothelackofuniformstandards,evenDBMSswiththesamedatamodelareoftendifferentintermsofuserinterfaceandsystemfunctions.

Whenauseroperatesadatabase,theDBMStakestheoperationfromtheapplicationprogramtotheexternallevel,theconceptuallevel,andthentotheinternallevel,andthenmanipulatesthedatainthememorythroughtheoperatingsystem(OS).Atthesametime,theDBMSisTheapplicationprogramopensaDBsystembufferinthememoryfordatatransmissionandformatconversion.Thethree-levelstructuredefinitionisstoredinthedatadictionary.

Technicalfeatures

(1)Acomplexdatamodelisusedtorepresentthedatastructure,withlowdataredundancy,easyexpansion,anddatasharing.

(2)Ithashighdataandprogramindependence,andtheindependenceofthedatabaseisphysicalIndependenceandlogicalindependence.

(3)Thedatabasesystemprovidesuserswithaconvenientuserinterface.

(4)Thedatabasesystemprovidesfouraspectsofdatacontrolfunctions,respectivelyItisconcurrencycontrol,recovery,integrity,andsecurity.Thedatausedbyeachapplicationinthedatabaseisuniformlyspecifiedbythedatabasesystem,organizedandestablishedaccordingtoacertaindatamodel,andmanagedandcontrolledbythesystem.

(5)Increasetheflexibilityofthesystem.

Application

1.Improvethesecurityofthedataencryptionsystem

ThecomputerdatabasemanagementsystemitselfcanencryptData,andcombiningitwithapuredataencryptionsystemcanimprovethesecurityofdata.However,itshouldbenotedthattheexistenceofanyinformationmanagementsystemisforpeople.Forthisreason,datainformationisprocessedinthisenvironmentTransmissionandmaintenancerequiretechnicalpersonneltofurtheroptimizethedataencryptionsystemtomeetpeople’sneeds.

2.Improvetheefficiencyofinformationstorage

ThebiggestadvantageofacomputerdatabasemanagementsystemliesintheabilitytoperformdataLong-termstorageandmanagementofinformation.Thisfeatureiswidelyusedinmanyfields.However,itshouldbenotedthattechnicalpersonnelshouldcarefullyidentifytheuser’sidentitywhenenhancingtheinformationstorageratetopreventtheintrusionofillegalusers.Reducemaliciousaccess,hackerattacksandotherissues,andtrulyensurethesecurityofdataandinformation.

3.Improvedatabackupandrecovery

Intheprocessofcomputernetworkapplications,informationloss,Systemcrashesandotherphenomenahavecauseddatainformationtobedamagedandcannotbeusednormally.Thecomputerdatabasemanagementsystemismainlyacollectionofdatastorage.Inthisstorageprocess,themanagementsystemwillstoredatainacertainmodeandestablishamorecomplexDatastructurerelationship.Thiscanrealizetheseparateprocessingofdata,aswellasthecombineduseandprocessingofdata,soastoachieveefficientdatarecovery.

4.Enhancedmultimediamanagement

Applicationofcomputerdatabasemanagementsystemcanimprovethemanagementlevelofmultimedia.Technicianscanusecomputerdatabasemanagementsystemtoreducethecomplexityofmultimediamanagement,reduceworkload,andimprovemultimediamanagementefficiency.

ExcellentClick

(1)Controldataredundancy.Databasemanagementshouldeliminateredundancyasmuchaspossible,butnotcompletely,buttocontroltheinherentredundancyofalargenumberofdatabases.Forexample,inordertoexpresstherelationshipbetweendata,therepetitionofdataitemsisgenerallynecessary,andsometimessomedataitemsarerepeatedinordertoimproveperformance.

(2)Ensuredataconsistency.Byeliminatingorcontrollingredundancy,theriskofinconsistencycanbereduced.Ifthedataitemisstoredinthedatabaseonlyonce,anyupdatetothevalueonlyneedstobedoneonce,andthenewvalueisimmediatelyobtainedbyallusers.Ifthedataitemisstoredmorethanonce,andthesystemisawareofthis,thesystemwillbeabletoensurethatallcopiesoftheitemareconsistent.Unfortunately,manyDBMSscannotautomaticallyensurethistypeofconsistency.

(3)Improvedatasharing.Thedatabaseshouldbesharedbyauthorizedusers.TheintroductionofDBMSmakesiteasierformoreuserstosharemoredata.Newapplicationscanrelyondatathatalreadyexistsinthedatabase,andonlyadddatathatisnotstoredwithoutredefiningalldatarequirements.

Examplesofdatabasemanagementsoftware

ThemostpopulardatabasemanagementsystemproductsonthemarketaremainlyproductsfromcompaniessuchasOracle,IBM,Microsoft,andSybaseandMysql.

OracleDatabase

Oracledatabaseisconsideredtobethemostsuccessfulrelationaldatabasemanagementsystemintheindustry.Oracle'sdatabaseproductsareconsideredtobenobleproductswithstableoperation,completefunctionsandsuperiorperformance.Forenterpriseswithlargeamountsofdata,busytransactionprocessing,andhighsecurityrequirements.Oracleisundoubtedlytheidealchoice.WiththepopularityofInternet,OraclehascloselyintegrateditsproductswithnetworkcomputingattherighttimetobecomealeaderintheInternetapplicationfieldofdatabasevendors.

OracledatabasecanrunonUnix,Windowsandothermainstreamoperatingsystemplatforms,fullysupportallindustrialstandards,andobtainthehighestlevelofISOstandardsecuritycertification.Oracleadoptsacompletelyopenstrategy,whichallowscustomerstochoosethemostsuitablesolution,whileprovidingfullsupporttodevelopers.

DB2

DB2isaproductofIBM.ItisamultimediaandWebrelationaldatabasemanagementsystem.Itsfunctionsaresufficienttomeettheneedsoflargeandmedium-sizedcompaniesandcanbeflexiblyservedinChinaSmalle-commercesolutions.TheIMS(InformationManagementSystem)introducedbyIBMin1968isatypicalrepresentativeofhierarchicaldatabasesystemsandthefirstlarge-scalecommercialdatabasemanagementsystem.In1970,IBMresearchersputforwardtherelationalmodelofthedatabasesystemforthefirsttime,pioneeringthestudyofdatabaserelationalmethodsandrelationaldatatheory,layingthefoundationfordatabasetechnology.100%oftheFortune100companiesand80010oftheFortune500companiesuseIBM'sDB2databaseproducts.AnotherveryimportantadvantageofDB2liesintherichnessofmatureapplicationsbasedonDB2.In2001,IBMmergedwithInformix,awell-knowndatabasecompanyrankedfourthintheworld,andincorporateditsadvancedfeaturesintoDB2,whichfurtherimprovedtheperformanceandfunctionsoftheDB2system.

Sybaseseries

SybasewasestablishedinNovember1984.Productresearchanddevelopmentincludeenterprise-leveldatabases,datareplicationanddataaccess.Themainproductsare:Sybase'sflagshipdatabaseproductAdaptiveServerEnterprise,AdaptiveServerRepli-cation,AdaptiveServerConnectandheterogeneousdatabaseinterconnectionoptions.SybaseASEisitsmaindatabaseproduct,whichcanrunonUnixandWindowsplatforms.SybaseWarehouseStudioprovidesspecializedanalysissolutionsincustomeranalysis,marketsegmentationandfinancialplanning.ThecoreproductofWarehouseStudioisAdaptiveServerIQ,anditspatenteddatastoragetechnologydesignedfromthebottomcanquicklyquerylargeamountsofdata.ThereisacompletesetoftoolsaroundAdaptiveServerIQ,includingthedesignofdatawarehousesordatamarts,theintegrationandtransformationofvariousdatasources,thevisualanalysisofinformation,andthemanagementofkeycustomerdata(metadata).

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