数据库系统概念(英文精编版.第六版)

2015年第1学期数据库系统公共360云盘Id:scau_db_2015password:scau_db_2015边山老师联系方式bianshan@126.com数学与信息学院611平时成绩占总评成绩的50%考勤作业和测验成绩实验成绩期末考成绩占总评成绩的50%卷面成绩60分以下则不计算平时成绩题型：选择题，应用题全英试题，答题用中文教材数据库系统概念，第6版，英文精编版ISBN:978-7-111-40086-8AbrahamSilberschatz,HenryF.Korth,S.Sudarshan机械工业出版社本课程学习内容关系数据模型关系数据库语言SQL关系代数关系数据库设计E-R模型范式理论事务管理并发控制故障恢复Chapter1:IntroductionPurposeofDatabaseSystemsViewofDataDatabaseLanguagesRelationalDatabasesDatabaseDesignDataStorageandQueryingTransactionManagementDatabaseArchitectureDataMiningandInformationRetrievalSpecialtyDatabasesDatabaseUsersandAdministratorsHistoryofDatabaseSystemsChapter1:Introduction教学目的：数据库系统的基础知识教学重点：数据的三个抽象层次、数据独立性模式和实例数据操作语言、数据定义语言数据模型、关系数据模型教学难点：数据的抽象层次PurposeofDatabaseSystemsDatabaseManagementSystem(DBMS)DBMScontains:Collectionofinterrelateddata(Database)SetofprogramstoaccessdataGoal:AnenvironmentthatisbothconvenientandefficienttouseExamples:Oracle,SQLServer,Access,MySQLDatabasestouchallaspectsofourlives:ATM,onlinebookstore……1.2PurposeofDatabaseSystemsIntheearlydays,databaseapplicationswerebuiltdirectlyontopoffilesystemsProblemsDataredundancyandinconsistencyNeedtowriteanewprogramtocarryouteachnewtask(eg.Findingoutthestudentswhocomefrom...)MultiplefilesandformatsIntegrityproblems»Integrityconstraints(e.g.accountbalance0)become“buried”inprogramcoderatherthanbeingstatedexplicitlyHardtoaddnewconstraintsorchangeexistingonesAtomicityofupdatesFailuresmayleadtoinconsistenciesExample:(1)account_A=account_A–100(2)account_B=account_B+100ConcurrentaccessbymultipleusersUncontrolledconcurrentaccessesmayleadtoinconsistenciesExample:(a1)A=account(a2)A=A–100(b1)B=account(a3)account=A(b2)B=B–100(b3)account=BSecurityproblemsHardtoprovideuseraccesstosome,butnotall,dataDatabasesystemsoffersolutionstoalltheaboveproblemsExercisesThevariouscopiesofthesamedatamaynolongeragree.Thispropertyiscalled()A.DatainconsistencyB.DataredundancyC.DataisolationD.Dataintegrity1.3ViewofDataHierarchyofAbstractionLevelsThreeAbstractionLevelsofDataPhysicallevel:describeshowdataisactuallystoredDatabasedevelopersusethislevel.Logicallevel:describeswhatdataarestoredinthedatabase,andwhatrelationshipsexistamongthosedataDatabaseadministratorsandapplicationprogrammersusethislevel.Viewlevel:simplifiestheinteractionwiththesystem.Viewscanalsohideinformationforsecuritypurposes.Computerusersusethislevel.ExamplesofLogicalLevelDataExamplesofViewLevelDataAviewthatshowstheinstructornamesoftheComputerSciencedepartment1.3.2InstancesandSchemasSchema–thelogicalstructureofthedatabaseExample:Instructor_schema=(ID,name,dept_name,salary)Department_schema=(dept_name,building,budget)Instance–theactualcontentofthedatabaseataparticularpointintimeDatabaseSystemProgrammingLanguageSchemaVariableTypeInstanceVariableValuePhysicalschema:describesdatabasedesignatthephysicallevelLogicalschema:describesdatabasedesignatthelogicallevelSubschema:describesviewsattheviewlevelExercisesComputerusersinteractswithdatainthe_______levelA.physicalB.logicalC.viewD.alloftheaboveApplicationusersinteractwithdatainthe_______level.A.physicalB.logicalC.viewD.alloftheaboveHowthedataareactuallystorediscalled_______A.PhysicallevelB.LogicallevelC.ViewlevelD.ConceptuallevelExercisesThecollectionofinformationstoredinthedatabaseataparticularmomentiscalled()A.InstanceB.SchemeC.PhysicalschemeD.DatarelationshipPhysicalDataIndependencePhysicalDataIndependenceIfthephysicalschemaismodified,thelogicalschemacanremainsunchanged,sodoestheapplicationprogramsIngeneral,theinterfacesbetweenthevariouslevelsandcomponentsshouldbewelldefinedsothatchangesinsomepartsdonotseriouslyinfluenceothers.1.3.3DataModelsAcollectionofconceptualtoolsfordescribingdata…Categories:RelationalModel(Chap2-8)Entity-RelationshipModel(Chap7)Object-baseddatamodelsSemistructureddatamodel(XML)Otheroldermodels:NetworkmodelHierarchicalmodelExercisesAdatamodelconsistsofA.schemaB.setofoperationsC.setofconstraintsD.allofA,B,andCRelationalModeltable,relationrow,record,tuplecolumn,attribute,field1.4DatabaseLanguages:DML&DDL1.4.1DataManipulationLanguage(DML)DataManipulationLanguageLanguagefordataretrieval,insertion,deletion,modificationQuerylanguageTheportionofaDMLthatinvolvesdataretrievalCommontousetheterms“datamanipulationlanguage”and“querylanguage”synonymously(同义)分两种:ProceduralDML(过程化)Declarative(声明式)(nonprocedural)DML特点userinstructsthesystemtoperformasequenceofoperationstoobtainthedataUserdescribesthedesireddata例子Relational-AlgebraSQLExercisesSQLisa_____languageA.proceduralB.nonproceduralRelational-Algebraisa_____languageA.proceduralB.nonprocedural1.4.2DataDefinitionLanguage(DDL)fordefiningthedatabaseschemaandconstraintsDDLcompilergeneratesasetoftablesstoredinadatadictionaryDatadictionarycontainsmetadata(i.e.,dataaboutdata)DatabaseschemaE.g.USER_OBJECTS,USER_TABLES,USER_VIEWSIntegrityconstraintsE.g.USER_CONSTRAINTS1.5RelationalDatabasesRelationalModeltable,relationrow,record,tuplecolumn,attribute