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1、SQL数据库英文文献及翻译ThefactthatyouarereadingabookonSQLindicatesthatyou,somehow,needtointeractwithdatabases.SQLisalanguageusedtodojustthis,sobeforelookingatSQLitself,itisimportantthatyouunderstandsomebasicconceptsaboutdatabasesanddatabasetechnologies.Whetheryouareaw
2、areofitornot,youusedatabasesallthetime.Eachtimeyouselectanamefromyouremailaddressbook,youareusingadatabase.IfyouconductasearchonanInternetsearchsite,youareusingadatabase.Whenyoulogintoyournetworkatwork,youarevalidatingyournameandpasswordagainstadatabase.Even
3、whenyouuseyourATMcardatacashmachine,youareusingdatabasesforPINnumberverificationandbalancechecking.Buteventhoughweallusedatabasesallthetime,thereremainsmuchconfusionoverwhatexactlyadatabaseis.Thisisespeciallytruebecausedifferentpeopleusethesamedatabasetermst
4、omeandifferentthings.Therefore,agoodplacetostartourstudyiswithalistandexplanationofthemostimportantdatabaseterms.ReviewingBasicConceptsWhatfollowsisaverybriefoverviewofsomebasicdatabaseconcepts.Itisintendedtoeitherjoltyourmemoryifyoualreadyhavesomedatabaseex
5、perience,ortoprovideyouwiththeabsolutebasics,ifyouarenewtodatabases.UnderstandingdatabasesisanimportantpartofmasteringSQL,andyoumightwanttofindagoodbookondatabasefundamentalstobrushuponthesubjectifneeded.WhatIsaDatabase?Thetermdatabaseisusedinmanyorganizedfa
6、shion.Thesimplestwaytothinkofitistoimagineadatabaseasafilingcabinet.Thefilingcabinetissimplyaphysicallocationtostoredata,regardlessofwhatthatdataisorhowitisorganizedDatabaseAcontainer(usuallyafileorsetoffiles)tostoreorganizeddata.MisuseCausesConfusionPeopleo
7、ftenusethetermdatabasetorefertothedatabasesoftwaretheyarerunning.Thisisincorrect,anditisasourceofmuchconfusion.DatabasesoftwareisactuallycalledtheDatabaseManagementSystem(orDBMS).ThedatabaseisthecontainercreatedandmanipulatedviatheDBMS.Adatabasemightbeafiles
8、toredonaharddrive,butitmightnot.Andforthemostpartthisisnotevensignificantasyouneveraccessadatabasedirectlyanyway;youalwaysusetheDBMSanditaccessesthedatabaseforyou.TablesWhenyoustoreinformationin
