会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

   首页 人人文库网 > 资源分类 > DOC文档下载

外文翻译--Designing a Database Application in VB 6.doc

  • 资源星级:
  • 资源大小:58.00KB   全文页数:7页
  • 资源格式: DOC        下载权限:注册会员
您还没有登陆,请先登录。登陆后即可下载此文档。
  合作网站登录: 微信快捷登录 支付宝快捷登录   QQ登录   微博登录
友情提示
2:本站资源不支持迅雷下载,请使用浏览器直接下载(不支持QQ浏览器)
3:本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰   

外文翻译--Designing a Database Application in VB 6.doc

DesigningaDatabaseApplicationinVB6.0AbstractBeforeyoustarttodesignadatabase,itsimportantyouunderstandexactlywhatadatabaseisandwhattypesofdatabasesyouhavetochoosefrom.Theapplicationtypewillaffectthedatabasetypethatyouchoose.WhatIsaDatabaseAdatabaseisreallyasystemthatcontainsmanydifferentobjectsusedtogethertoallowyourapplicationfastandefficientaccesstothedata.Youcanusemanyexamplesofdatabaseswithyourapplication.ThemostcommonoftheseareasfollowsMicrosoftAccessMicrosoftFoxProOraclePersonalEdition7ior8iandMSSQLServer7.00isonlyafewtomention.Allthesedatabasescanrunonastandalonecomputerandallowyoutocreateverycomplexdatabasesforyourapplications.Pickingtherightdatabaseforyourapplicationisextremelyimportant,becausethewrongonewillaffectperformanceandmakeyourjobasadevelopersomuchmoredifficult.Beforestartingthedesignprocess,youneedtoselectadatabase.WhenworkingwithVisualBasic,thedatabasethatyoucanchoosefromfallintotwodistinctgroupsLocalDatabasescanbeaccesseddirectlyfromVisualBasicthroughVisualBasicsdatabaseJetengineandRemotedatabasescannotbeaccessedbyusingVisualBasicsstandarddatabaseaccesscapabilities.Understandingthedifferenceswillhelpyouselectthecorrectdatabaseforyourapplication.However,inVisualBasic6,thereisnowawaytoaccessbothlocalandremotedatabasesusingthesamedatabaseaccesscontrolsandobjectsknownastheActiveXDataObjects.UnderstandingUniversalDataAccessUDAAsdatabaseshavegrownandmovedoffthelocalcomputerandontonetworkeddatabaseservers,themethodsemployedtoaccessthedatabaseshavechanged.Microsofthasaddressedthesechangesbydevelopingstrategytoallowforanycompanyordatabasetobeaccessedthesameway.ThisiscalledUniversalDataAccess,orUDA.UnderstandingwhatUDAmeansisnotassimpleasunderstandingtouseit.ThereasonforthisisthatUDAisasetofrulesandaccessmethodsthatmustbefollowedbyanycompanythatiscreatingadatabaseaccessmethodtobeused.Thisallowsyou,theprogrammer,toaccessanydatabasethesamewayButwhatisUDAUniversalDataAccessisaplatform,applicationsandtoolsconceptthatMicrosofthasdevelopedthatdefinesanddeliversthestandardsforallfutureapplicationdevelopment.UsingUDAstandardswillprovidehighperformanceaccesstomanytypesofdataandinformationthatresideonmultipleplatforms,andaprogramminginterfacethatwillworkwithalmostanytoolorlanguageusingtheskillsthatdevelopersalreadyhave.ThisisaccomplishedbyusingMicrosoftsDataAccessComponentsMDAC,aswellasanintegratedsetoftechnologies,whichincludeActiveXDataComponentsADO,OLEDB,andOpenDatabaseConnectivityODBC.ThebenefitsofusingthesestandardsincludethefollowingHighperformanceaccesstodata–ProvidestheabilitytoscaleanyapplicationorcomponenttosupportconcurrentlyconnecteduserswithoutlosingperformanceReliability–ReducesthenumberofcomponentstosupportontheclientPCandWideindustrysupport–ManyvendorsincludingMicrosofthavealreadyannouncedsupportfortheUDAstandards.InpreviousreleasesofVisualBasic,youneededtochoosefromeitherDAOlocalaccessmethodstodataorRDOremoteaccesstodata.Now,withthesupportofUDA,VisualBasichasathirdmethodfordataaccesscalledADO,orActiveXDataObjects.Thisallowsyoutocombinethedifferentwaysofaccessingdataintoonesetofprogrammingcallsandobjects.ADOworksinconjunctionwithOLEDBandODBCtoprovideaccesstoonedatabaseyoumightbeworkingwith.Gettingforward,MicrosoftplanstophaseoutODBCinfavourofOLEDBandtheUDAstandards.However,forthenearfuture,DAOandRDO,aswellasODBC,willstillbesupportedtoallowdeveloperstoslowlymoveuptothenewstandardsofdataaccess.LocalDatabasesLocaldatabasesaregenerallymuchsmallerthantheremotetypeofdatabase.ThefollowingdatabasesfallintothiscategoryMicrosoftAccessMicrosoftFoxProLotusWorksheetsMicrosoftExcelWorksheetsdBaseParadoxandASCII.Asyoucansee,thesePCresidentdatabasetypeshavebeenaroundforawhileandareavailablefromalmostanycomputersoftwarestore.AccessingthesedatabasesdoesntrequireanyothersoftwaretobeinstalledonthePC,nordoesitrequirespecialknowledgeonhowtoworkwiththem.However,thesizeoflocaldatabasesisrestricted.MicrosoftAccess97databasescantexceed1GBgigabyte.Localdatabasesaregenerallyusedforsingleuserapplicationssuchascheckbooks,addressbooks,andpersonalinformationmanagers.Someenterprisingteenagershavecreateddatabaseapplicationsthathelpthemkeeptrackofbaseballcardsorvideotapes.Soindecidingwhatyourapplicationwilladdressandhowitwillbeusedactuallyhelpsyouinthedatabaseselectionprocess.RemoteDatabasesBydefinitionremotedatabasesdontresideontheusersPC,butthisisnotalwaystrue.Infact,aremotedatabaseisanytypeofdatabasethatrequiresanODBCOpenDatabaseConnectivitydriverforanapplicationtoaccessit.ODBCdatabasesfallintotwomaincategoriesonethatrunonasinglePCandthelargercorporateonesthatrequirelarge,verypowerfulcomputerscalledserverswithlargeamountsofavailablediskspace.DatabaseserversareusedtoseparatetheworkloadbetweentheclientPCwheretheapplicationexecutesandthedatabasesystemwherethedatabasequeriesareperformed.ThisprovidestheapplicationwithfastdataaccesswithoutslowingdowntheusersPC.MostthelargeservertypedatabasesprovideversionsthatwillrunonstandalonePCs.MostlargecorporationsuseoneofthefollowingdatabasesystemsthoughthisisnottosaythatothersarentoutthereOracleSybaseandMicrosoftSQLServer.UsingaremotedatabaserequiresyoutouseeithertheremotedatabaseobjectsavailableonlyintheEnterpriseversionofVisualBasic6orthenewActiveXDataObjectsavailableinallreleasesofVisualBasic6.Ifyouredesigninganapplicationthatwilluseoneoftheselargedatabases,however,thebestwaytocreatetheapplicationthatwillusethesinglePCversionduringthedesign,developmentandtestingprocess.Then,wewhentheapplicationiscompleted,switchtoODBCconnectiontothelarger,serverbasedversion.BuildingtheInitialDesignCreatinganapplicationisalotlikebuildingahouse.Forawellbuilthouse,youneedablueprinttofollow,buttocreateagoodblueprint,youneedtoknowwhosgoingtoliveinthehouseandwhattheirlivingstyleswillbe.Thiswillhelpyoudecidethenumberandsizesofthebedrooms,whatcolourstouse,andsoon.Withanapplication,theblueprintisthetechnicalspecificationsthefunctionalspecificationsarewhatyouneedtoknowtocreatethetechnicalspecifications.Now,manybooksteachtheoverallapplicationdesignprocessbyusingverysimplisticexampleapplications.ThedescriptionoftheapplicationwemustdevelopisasfollowsPersonalAddress/PhoneBook–Thisapplicationwillkeeptrackofnames,addresses,andphonenumbersbyname.Itwillallowasmanydifferentaddressesandphonenumbersasneeded.Also,itwillallowtheentryofsomepersonalinformationsuchasbirthdate,spousesname,andchildrennamestobedeterminedlater.Itwillalsoprovidereportsinseveralformatsandallowuserstosearchthedatabaseforaparticularperson.ChoosingtheTasksDefiningtasksfortheapplicationalsodefinesitscomplexity.Forexample,thisapplicationisanaddress/phonebook,ifyoudecidetogiveuserstheabilitytoselectaphonenumberandhavethecomputerdialitforthem.Toaddthisfunctionalitytotheapplication,youneedtoknowhowtotestfortheexistenceofthemodem,connecttothatmodem,andthenactuallydialthatnumber.Ifyoudontknowhowtoaddthisfunctionality,youmightconsiderwaitingtoadditaftertheinitialversionoftheapplicationiscreatedandtested.Thisiswhatreleasingnewversionsareallabout.Keeptheinitialversionofthisapplicationatasimplerlevel.Thebestwaytodesignanapplicationistosaytoyourself,WhatwouldIwanttheapplicationtodoifIweretheuserBasically,yourethefirstandmostimportantuseroftheapplication.Thisapproachmightnotworkforthelarger,corporatetypeapplication,butitdoesworkforthesmaller,morepersonaltypes.Evenbeforeyoulistthedifferenttasksthattheapplicationwillperform,youneedtodecidewhattypeofapplicationinterfacetouseforthisapplication.Forthissampleapplication,usetheExplorerstyleinterface.Toreviewthisstyle,theinitialformthatusersseeandremaininformostoftheapplicationwillresembletheoneshowninFigure1.Figure1Thisinterfaceincludesmanyofthecontrolsthatyouhavelearnedearlier.Okay,wehavepickedtheapplicationthatyoullcreate–nowyouneedtolistthemainfunctionsthatitwillperform.Thinkofwhattheapplicationisforandthenlistwhatyouwantittodo.Fromthisreasoning,youshouldgetthefollowinglistKeepnamesandaddressesSearchforaparticularnamePrintdifferenttypesofreportsAllowfordifferentusersandEnableeasymaintenanceoftheapplication.Now,ifthislistseemssimplistic,itisYouwouldthenexpandeachiteminthislistuntilyouresatisfiedwiththeresult.Letsexpandeachoftheprecedingtasksandaddamoredetailtothedefinition.KeepingNamesandAddressesWhatdoyoureallymeanwhenyousayKeepnamesandaddressesItusuallymeansthatyouwanttokeeptrackofthestandardinformationfoundinanystandardtelephonebookyoulookat.Thefirststepindefiningalltheminitasksrequiredforthistopicistolistthedataelementsyouwanttoputinthedatabase.Table1liststhedataelementsthatyoucanuseforthistypeofapplication.NameTypeFirstNameStringLastNameStringSpouseNameStringChildNameStringAddressStringCityStringStateStringZIPIntegerEMailAddressStringPhoneLongBirthDateDateNotesStringTable1DataElementsThatCanBeIncludedInTheApplicationDatabase.

注意事项

本文(外文翻译--Designing a Database Application in VB 6.doc)为本站会员(英文资料库)主动上传,人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知人人文库网([email protected]),我们立即给予删除!

温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。

copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5