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1、數(shù)據(jù)庫(kù)基礎(chǔ)知識(shí)培訓(xùn)膠片集成產(chǎn)品部數(shù)據(jù)庫(kù)原理目標(biāo)通過(guò)這部分課程的學(xué)習(xí),您將了解以下內(nèi)容:關(guān)系數(shù)據(jù)庫(kù)基本概念常用數(shù)據(jù)庫(kù)對(duì)象常用數(shù)據(jù)類型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
