数据库基础知识培训胶片.ppt

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1、数据库基础知识培训胶片集成产品部数据库原理目标通过这部分课程的学习,您将了解以下内容:关系数据库基本概念常用数据库对象常用数据类型INDatabaseInformixServerSMPSCPSMAPSMAPSMAPThedatabaseplaystheroleofthebase,savingandprocessingthedatathatshouldbeeasilyaccessedbytheuser.Whatisadatabase?Usually,adatabaserunsintheserverparttoservea

2、ccessrequestsfromclients.DBClient(DBA)DBDBServerDBClient(User)DBClient(User)UsersuseDDLtodefineadatabaseUsersuseDMLtooperatedatainadatabaseUsersuseprogramstomanagedatabaseDDL,DML&ProgramsTablesAdatabaseinaRDBMSisacollectionofinformationthatisgroupedintooneormore

3、tables.Atableisanarrayofdataitemsorganizedintorowsandcolumns.StockPPSServiceDataTableINServiceDatabaseFPHServiceDataTableSubscriberDataTableTablesarerelationalSubIDBalanceIDDFlag1001100.0001012200.001MSISDNNumBalanceIDDFlagSubID1001100.0001001012200.001101FPHNum

4、BalanceIDDFlagSubID80081012341100.00010080081043212200.001101RowsRowsEachrowofatablestandsforoneinstanceofthesubjectofthetable,whichisoneparticularexampleofthatentity.StockColumnsEachcolumnofatablestandsforoneattribute,whichisonecharacteristic,feature,orfactthat

5、istrueofthesubjectofthetable.ColumnsStockOperationsonTablesDatabaseObjectsObjectDescriptionTableBasicunitofstorage;composedofrowsandcolumnsViewLogicallyrepresentssubsetsofdatafromoneormoretablesSequenceNumericvaluegeneratorIndexImprovestheperformanceofsomequerie

6、sSynonymGivesalternativenamestoobjectsWhatisaView?EMPLOYEESTable:WhyUseViews?TorestrictdataaccessTomakecomplexquerieseasyToprovidedataindependenceTopresentdifferentviewsofthesamedataWhatareConstraints?Constraintsenforcerulesatthetablelevel.Constraintspreventthed

7、eletionofatableiftherearedependencies.Thefollowingconstrainttypesarevalid:NOTNULLUNIQUEPRIMARYKEYFOREIGNKEYCHECKWhatisanIndex?Anindex:IsaschemaobjectIsusedbytheOracleservertospeeduptheretrievalofrowsbyusingapointerCanreducediskI/Obyusingarapidpathaccessmethodtol

8、ocatedataquicklyIsindependentofthetableitindexesIsusedandmaintainedautomaticallybytheOracleserverHowAreIndexesCreated?Automatically:Auniqueindexiscreatedautomatically