ch1_intronew

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1、DatabaseManagementSystemsChapter1Instructor:RaghuRamakrishnanraghu@cs.wisc.eduDatabaseManagementSystems3ed,R.RamakrishnanandJ.Gehrke1WhatIsaDBMS?Averylarge,integratedcollectionofdata.Modelsreal-worldenterprise.
Entities(e.g.,students,courses)
Relationships(e.g.,M

2、adonnaistakingCS564)ADatabaseManagementSystem(DBMS)isasoftwarepackagedesignedtostoreandmanagedatabases.DatabaseManagementSystems3ed,R.RamakrishnanandJ.Gehrke2Filesvs.DBMSApplicationmuststagelargedatasetsbetweenmainmemoryandsecondarystorage(e.g.,buffering,page-ori

3、entedaccess,32-bitaddressing,etc.)SpecialcodefordifferentqueriesMustprotectdatafrominconsistencyduetomultipleconcurrentusersCrashrecoverySecurityandaccesscontrolDatabaseManagementSystems3ed,R.RamakrishnanandJ.Gehrke3WhyUseaDBMS?Dataindependenceandefficientacce

4、ss.Reducedapplicationdevelopmenttime.Dataintegrityandsecurity.Uniformdataadministration.Concurrentaccess,recoveryfromcrashes.DatabaseManagementSystems3ed,R.RamakrishnanandJ.Gehrke4?WhyStudyDatabases??Shiftfromcomputationtoinformation
atthe“lowend”:scrambletowe

5、bspace(amess!)
atthe“highend”:scientificapplicationsDatasetsincreasingindiversityandvolume.
Digitallibraries,interactivevideo,HumanGenomeproject,EOSproject
...needforDBMSexplodingDBMSencompassesmostofCS
OS,languages,theory,“A”I,multimedia,logicDatabaseManagementS

6、ystems3ed,R.RamakrishnanandJ.Gehrke5DataModelsAdatamodelisacollectionofconceptsfordescribingdata.Aschemaisadescriptionofaparticularcollectionofdata,usingtheagivendatamodel.Therelationalmodelofdataisthemostwidelyusedmodeltoday.
Mainconcept:relation,basicallyatabl

7、ewithrowsandcolumns.
Everyrelationhasaschema,whichdescribesthecolumns,orfields.DatabaseManagementSystems3ed,R.RamakrishnanandJ.Gehrke6LevelsofAbstractionManyviews,singleView1View2View3conceptual(logical)schemaandphysicalschema.ConceptualSchema
Viewsdescribehowuser

8、sseethedata.PhysicalSchema
Conceptualschemadefineslogicalstructure
Physicalschemadescribesthefilesandindexesused.*SchemasaredefinedusingDDL;datai