ERwin使用說明(中英文)

經(jīng)典word整理文檔，僅參考，轉(zhuǎn)Word此處可刪除頁眉頁腳。本資料屬于網(wǎng)絡(luò)整理，如有侵權(quán)，請聯(lián)系刪除，謝謝！GettingStartedwithER(Erwinwin入門)byDr.PeterWolcottDepartmentofInformationSystemsandQuantitativeAnalysisCollegeofInformationScienceandTechnologyUniversityofNebraskaatOmaha（由內(nèi)布拉斯加州的奧馬哈大學(xué)信息科學(xué)與技術(shù)學(xué)院門的信息系統(tǒng)和定量分析博士彼得著）Introduction（介紹）ERwinisapopulardatamodelingtoolusedbyanumberofmajorcompaniesinOmahaandthroughouttheworld.（Erwin是受奧馬哈和世界各地的一些主要的公司歡迎的數(shù)據(jù)模型工具）Theproductiscurrentlyowned,developed,andmarketedbyComputer,aleadingsoftwaredeveloper.（該產(chǎn)品是由具有領(lǐng)導(dǎo)地位的CA軟件開發(fā)公司擁有、開發(fā)和銷售）Theproductsupportsavarietyofaspectsofdatabasedesign,includingdatamodeling,forwardengineering(thecreationofadatabaseschemaandphysicaldatabaseonthebasisofadatamodel),andreverseengineering(thecreationofadatamodelonthebasisofanexistingdatabase)forawidevarietyofrelationalDBMS,includingMicrosoftAccess,Oracle,DB2,Sybase,andothers.該軟件為多種多樣的關(guān)系型數(shù)據(jù)庫管理系統(tǒng),包括MicrosoftAccess,甲骨文,Sybase,DB2,和其他人提供支持?jǐn)?shù)據(jù)庫設(shè)計(jì)的各個(gè)方數(shù)據(jù)庫）和逆向工程（在現(xiàn)在的數(shù)據(jù)庫基礎(chǔ)上創(chuàng)建數(shù)據(jù)模型）ThisbrieftutorialstepsyouthroughtheprocessofcreatingadatamodelwinusingER.（你可以通過這個(gè)簡單教程中的步驟運(yùn)用Erwin來創(chuàng)建數(shù)據(jù)模型）ItwillnotexplainallaspectsofERwin,butwillshowyoutheminimumnecessarytocreateandusedatamodelsforthisclass.（這個(gè)課程不可能全面地講解Erwin模型的知識）Itconsistsofthreemajorsegments,whichcorrespondtotheproject-relatedassignmentsinyourclass:（這個(gè)課程由三個(gè)主要部分組成，它與有關(guān)項(xiàng)目任務(wù)相符）1.Creationofabasicdatamodel(Conceptualdatamodel)創(chuàng)建一個(gè)基本的數(shù)據(jù)模型(概念數(shù)據(jù)模型)2.Creationofadatabaseschema建立數(shù)據(jù)庫模式3.Creationofthedatabase創(chuàng)建數(shù)據(jù)庫Thistutorialisastaticone,suitableforprinting.本教程是一個(gè)靜態(tài)的,適合印刷Atutorialusingscreencapturesandnarrationisalsoavailable.一個(gè)指南使用屏幕捕捉和敘述是可用的。Section1.CreationofabasicdatamodelYouwillbecreatingadatamodelsimilartothatcreatedfortheHeartlandPropertiescasestudyusedinclass.教程中你將創(chuàng)建一個(gè)和研究心臟地帶個(gè)案相似的數(shù)據(jù)模型TheEntitiesinvolvedinthismodelinclude:Employee,Office,Property,andInspection.參與本次的實(shí)體模型包括:員工、辦公、財(cái)產(chǎn)、及檢驗(yàn)。First,invokeERwinfromStart->Programs->ComputerAssociates->AllFusion->ERwinDataModeler->Erwin首先，從開始——程序——CA——所有程序——ERwinDataModelerYouwillfirstencounteradialogboxentitled"ModelMartConnectionManager"（經(jīng)理ModelMart連接）.SimplyclickonCancel.將首先遇到一個(gè)對話框題為“ModelMartConnectionManager”。只需點(diǎn)擊“取消”。Youwillbeaskedtochoosebetweencreatinganewmodel,andopeninganexistingmodel,asshowninFigure1你將被要求之間作出選擇,創(chuàng)造了一種新的模式,開放一個(gè)現(xiàn)有的模型,如圖1所示.Forthisexercise,createanewmodel.通過這個(gè)練習(xí),創(chuàng)建一個(gè)新的模型Figure1:CreateanewmodelThenextdialogbox,showninFigure2,willaskyoutochoosethetemplatetobeusedtocreatethenewmodel.下一個(gè)對話框,如圖2所示,會(huì)讓你選擇的模板可以被用來創(chuàng)造新的模型Atthispoint,youmayassociatethemodelwithatargetDBMSproduct,suchasMicrosoftAccess,Oracle,DB2,etc.在這一點(diǎn)上,你可以把這個(gè)模型與如MicrosoftAccess,甲骨文,DB2等目標(biāo)數(shù)據(jù)庫產(chǎn)品聯(lián)系在一起Youwillhavetheopportunitytochangethischoicelater,butfornowchooseMicrosoftAccess.你之后將有機(jī)會(huì)改變這種選擇,但是現(xiàn)在選擇MicrosoftAccess。Also,chooseLogical/Physicalasthenewmodeltype.同時(shí),選擇的邏輯或者物理作為新模型形式Thischoicewillallowustoswitchbackandfortheasilybetweenalogicalmodel(ERDiagram)andaphysicalmodel(databaseschema).這個(gè)選擇將讓我們輕易之間來回切換邏輯模型(ER圖)和物理模型(資料庫)Figure2:SelectingamodeltypeERwinwillnowdisplaythemainwindowfromwhichmostofyourERdiagramdevelopmentwillbedone,asshowninFigure3.ERwin現(xiàn)在將顯示在主窗口大部分你ER圖發(fā)展來完成,如圖3。Figure3:TheERwinWorkplaceERwin工作場所TheERwinworkplaceconsistsoftwomainparts.OntheleftistheModelNavigator,whichdisplaysahierarchyofitemsofimportance,suchasentities,domains,andsubjectareas.左面是模型的領(lǐng)航員,顯示某一層次的物品的重要性,如實(shí)體、領(lǐng)域和課題。OntherightistheDisplayWindow,whichwillshowtheERdiagramitself.右邊是顯示窗口,它能夠顯示ER圖本身Asyoucreateobjects,theywillappearinthedisplaywindow(iftheyarevisualinnature,likeentities),andappearinthehierarchywithintheModelNavigator.當(dāng)你創(chuàng)建對象時(shí),他們將會(huì)出現(xiàn)在顯示器窗口(如果它們是視覺的自然屬性,就像實(shí)體),并將出現(xiàn)在層級模型導(dǎo)航器。AtoollikeERcanaccomodateanumberofdatamodelingnotationsandwinconventions.像ER這樣工具可以容納大量的數(shù)據(jù)建模的符號和對話Inmyclasspleasemakethefollowingchangestothepreferencesbeforeyoubegintocreateyourmodel在我的課上請完成下面的改變的偏好,在你開始之前,創(chuàng)造你的模型:1.FromtheFormat->EntityDisplaymenu,makesurethatPrimaryKeyDesignatoris2.FromtheFormat->EntityDisplaymenu,makesurethatForeignKeychecked.從格式-實(shí)體顯示菜單,確保外國關(guān)鍵checked從格式->實(shí)體顯示菜單,確保主鍵欄進(jìn)行檢查Designator(FK)is指示器(FK)是不能檢查3.FromtheFormat->EntityDisplaymenu,makesurethatShowMigratedchecked.從格式->實(shí)體顯示菜單,確保顯示屬性遷移Attributesischecked到4.FromtheFormat->RelationshipDisplay,makesurethatVerbPhraseischecked.從格式-關(guān)系顯示、確保動(dòng)詞短語進(jìn)行檢查Inaddition,youmaychoosebetweentwodifferentE-Rdiagrammingnotations.另外,你可以選擇兩種不同的e-r種畫圖符號InERwin,clickonModel->ModelPropertiestoseethewindowshowninFigure3b:點(diǎn)擊模型->窗口模型屬性看到如圖3b.Figure3b:ChoiceofnotationThistutorialisbasedontheInformationEngineering("CrowsFoot")notation.YoumayalsouseIDEF1X,ifyouwish.本教程是基于信息工程(“烏鴉腳”)的符號。你也可以使用IDEF1X,如果你愿意的話。Tocreateanewentity,clickontheentityicon()onthetoolbar,orright-clickonthewordintheModelNavigator.創(chuàng)建一個(gè)新的Entity實(shí)體,點(diǎn)擊實(shí)體工具欄上的圖標(biāo)(),或者以右鍵點(diǎn)擊這個(gè)詞中的實(shí)體模型導(dǎo)航器Ifyouclickontheentityicon,youthenshouldclickontheDisplayWindowwhereyouwouldliketheentitytoappear,asshowninFigure4.如果你點(diǎn)擊了實(shí)體圖標(biāo),那么你應(yīng)該點(diǎn)擊顯示窗口,在那里你會(huì)喜歡這個(gè)實(shí)體出現(xiàn)的各位朋友,如圖4所示Figure4:AnewentityNoticethatthedefaultnamefortheentityisE/x,wherexissomenumber(2inthiscase).注意,默認(rèn)的名字因?yàn)閷?shí)體是E/x,那里的x是一些數(shù)字(2在這種情況下)ClickontheTabkeyseveraltimesandnoticewhathappens.點(diǎn)擊Tab鍵了好幾次,通知會(huì)發(fā)生些什么PressingthetabkeycausethefocustocyclebetweenthethreemainpartsoftheEntity:按tab鍵引起關(guān)注焦點(diǎn),周期之間的三個(gè)主要部分的實(shí)體thenameoftheentity,theprimarykeyattribute(s)主要的關(guān)鍵屬性,andthenon-primarykeyattribute(s)時(shí)速的關(guān)鍵屬性(s).Ingeneral,tomodifyoneofthesethreepartsoftheTabentity,youwillpressthekeytocycletotheappropriatepartoftheentity,thentypetoaddormodifythatpartoftheentity.一般來說,修改這三部分的實(shí)體,你會(huì)按Tab鍵循環(huán)到適當(dāng)?shù)囊徊糠?然后輸入實(shí)體的增加或修改的那部分實(shí)體TabRightnow,pressthekeyuntiltheentitynameishighlighted.現(xiàn)在,按Tab鍵,直到實(shí)體名稱是突出了ThentypeEMPLOYEE,asshowninFigure5.然后輸入雇員,如圖5。Figure5:ChangingthenameoftheentityAtthispoint,youmaywishtosaveandnameyourdiagramtoavoidlossshouldthesystemorapplicationcrash.在這一點(diǎn)上,你可能想要存起來,說出你的圖來避免損失應(yīng)該系統(tǒng)或應(yīng)用程序崩潰。OnceyouhavechangedthenametoEMPLOYEE,presstheTabkeyagaintomovethefocustothenextpartoftheEntity,addingaprimarykeyattribute.一旦你已經(jīng)更改了名稱給員工,按Tab鍵來移動(dòng)焦點(diǎn)再下一部分的實(shí)體,添加一個(gè)關(guān)鍵屬性Thentypethenameoftheprimarykeyattribute,Emp_Num,asshowninFigure6.然后輸入名稱的屬性,Emp_Num主鍵,如圖6。Figure6:AddingaprimarykeyattributeNoticethatbecauseofthepreferencesyousetearlier,theprimarykeyattributehasakeyiconnexttoit.值得注意的是,因?yàn)槟愕南埠迷O(shè)定早些時(shí)候,主鍵的屬性是一個(gè)關(guān)鍵的圖標(biāo)旁邊。PresstheTabkeyonemoretimetobringthefocusbelowthehorizontallineintheEntity,whereyouwilladdinanumberofnon-primarykeyattributes.按Tab鍵一遍把焦點(diǎn)的水平線以下的實(shí)體,在那里您將加入一定數(shù)量的時(shí)速關(guān)鍵屬性。TypeEmp_Fname,asshowninFigure7.Emp_Fname型,如圖7WhenyouhavetypedEmp_Name,Enterkey(notTab)當(dāng)你打了Emp_Name,按回車鍵(不是選項(xiàng)pressthe卡).Noticewhathappens當(dāng)你學(xué)得.ThecursorisnowpositionedforyoutoaddanotherattributeinthissameportionoftheEntity,thenon-primarykeyattributeportion.定位光標(biāo)被現(xiàn)在你添加另一個(gè)屬性在這個(gè)相同的部分實(shí)體、時(shí)速關(guān)鍵屬性分。Figure7:Addingnon-primarykeyattributesContinueaddingthefollowingnon-primarykeyattributes:繼續(xù)增加下列時(shí)速關(guān)鍵屬性:Emp_LnameEmp_SSNEmp_StreetEmp_CityEmp_StateEmp_ZipcodeEmp_PhoneEmp_FaxYourdiagramshouldnowlooklikeFigure8.Figure8:TheEmployeeentityRepeattheentitycreationprocessfortheentitiesandattributeslistedinTable1.重復(fù)這個(gè)實(shí)體創(chuàng)建過程中為實(shí)體及其屬性列于表1。Man_Car_AllowanceASSOCIATEAssoc_Hourly_RateTable1:EntitiesandAttributesNoticethatsomeoftheentitieshavenoprimarykeyattributes(Manager,Associate),andoneentityhasanattributewhichispartoftheprimarykey,butbyitselfdoesnotconstituteaprimarykey(Inspection).注意到一些實(shí)體屬性沒有主鍵(),和一個(gè)實(shí)體有一個(gè)屬性的一部分,而是由主鍵本身并不會(huì)構(gòu)成一個(gè)主鍵(檢驗(yàn))Asweaddrelationshipstothediagram,thenatureofthekeysfortheseentitieswillbecomeclear.當(dāng)我們添加關(guān)系圖,大自然的鑰匙,這些實(shí)體就變得清晰了Forthetimebeing,besurethattherearenoprimarykeyattributesforManagerandAssociate,andonlyoneprimarykeyattributeforInspection,asshowninFigure9.隨著時(shí)間的推移,要確保沒有關(guān)鍵屬性對經(jīng)理及員工,只有一個(gè)主要的關(guān)鍵屬性進(jìn)行檢驗(yàn),如圖9所示Figure9:HeartlandPropertiesEntitiesERwinsupportsthecreationofrelationshipswiththreebasickindsofconnectivity（ERwin支持創(chuàng)造之間的關(guān)系三種基本的連通性:one-to-one,winone-to-many,andmany-to-many.Withintheone-to-manycategory,ERallowsustodistinguishbetweenidentifyingandnon-identifyingone-to-manyrelationships.這一對范疇,ithin歐文允許我們區(qū)分識別和non-identifying一對多的關(guān)系。One-to-manyRelationshipsWe'llbeginwithtworelationships,betweenInspectionandEmployeeandbetweenInspectionandProperty.我們可以先開始兩個(gè)關(guān)系,檢驗(yàn)和員工之間,檢驗(yàn)和財(cái)產(chǎn)的權(quán)利之間InspectionisrelatedtobothPropertyandEmployeeinonetomanyrelationships.同時(shí)與檢驗(yàn)是財(cái)產(chǎn)和員工在一對多的關(guān)系EachInspectionisundertakenatoneProperty;在進(jìn)行每個(gè)檢查是一套房產(chǎn)eachPropertymayundergomanyinspections每處房產(chǎn),可能經(jīng)過許多檢查.EachInspectioniscarriedoutbyoneEmployee每次檢驗(yàn)進(jìn)行了一名員工;eachEmployeecarriesoutmanyInspections每一位員工進(jìn)行許多檢查.Aretheserelationshipsnon-identifyingrelationships?這些是關(guān)系識別關(guān)系或non-identifying關(guān)identifyingrelationshipsoridentifyingrelationshipsor系嗎?Aretheserelationshipsnon-identifyingrelationships?這些是關(guān)系識別關(guān)系或non-identifying關(guān)系嗎?TheissuehingesonthenatureoftheprimarykeyofInspection,theentityonthe"many"sideoftherelationship.問題的關(guān)鍵在于性質(zhì)的主鍵的檢驗(yàn)、實(shí)體上的“許多”方面的關(guān)系。TheprimarykeyofInspectioninthisexampleisacompositeprimarykeyconsistingoftwoattributes主鍵的檢驗(yàn)在本例中是一個(gè)合成物,主鍵由兩個(gè)屬性:{Insp_Date,Prop_ID}ThebusinessruleineffecthereisthateachpropertyhasatmostoneinspectionperdayInsp_DateProp_ID}的商業(yè)規(guī)則,在這里,每一種性質(zhì)影響的條件下,在大多數(shù)人檢查每天.Onemightarguewhetherornotthatisasoundassumption,butletssupposeforthesakeofillustrationthatitis.一個(gè)人可能會(huì)爭辯說不管那是一種合理的假設(shè),但為了說明我們可以假設(shè)它是。NoticethattheprimarykeyofInspectionincludestheprimarykeyofProperty,theentitywithwhichithasarelationship.值得注意的是,主鍵檢查包括主鍵的性質(zhì)、實(shí)體與它有關(guān)系Forthisreason,wesaythattherelationshipbetweenInspectionandPropertyisanidentifyingone-to-manyrelationship.因?yàn)檫@個(gè)原因,我們說,檢驗(yàn)和財(cái)產(chǎn)之間的關(guān)系是一種識別一對多的關(guān)系。Anidentifyingrelationshipiscreatedbyclickingfirstontheidentifyingrelationshipicon().創(chuàng)建一個(gè)識別關(guān)系是通過點(diǎn)擊第一的在識別關(guān)系圖標(biāo)()Noticethatithasthecrow'sfootnotation(indicating"many")andasolidline(indicatingidentifying).值得注意的是,它有烏鴉腳的符號()和一個(gè)實(shí)線(指著識別)Tocreateanidentifyingrelationship,clickfirstonthisicon,thenclickontheparententity(ontheonesideoftherelationship)andthenclickonthechildentity(onthemanysideoftherelationship).創(chuàng)建一個(gè)識別關(guān)系,點(diǎn)擊先在這個(gè)圖標(biāo),然后點(diǎn)擊“家長實(shí)體(在這邊的關(guān)系),然后點(diǎn)擊孩子實(shí)體(在許多一端的關(guān)系)Inthiscase,youwillclickfirstontheidentifyingrelationshipicon,thenonProperty,thenonInspection.在這種情況下,你就會(huì)點(diǎn)擊圖標(biāo)先識別,然后在產(chǎn)權(quán)關(guān)系,然后在檢查TheresultsareshowninFigure10.結(jié)果顯示于圖10Figure10:AnidentifyingrelationshipNoticethatERwinhasprovidedalabel"R/1"fortherelationship,whichisnotveryhelpful.值得注意的是,win已經(jīng)提供了一個(gè)標(biāo)簽"R/”的關(guān)系,而不是很有幫助Double-clickontherelationshipitselftobringupadialogboxinwhichwecanfurtherrefinetherelationshipdefinition雙擊關(guān)系本身造就了一個(gè)對話框,以這種方式我們能夠進(jìn)一步提煉的關(guān)系的定義.FilloutthisdialogboxasshowninFigure11.填寫這對話框如圖11分Figure11:RelationshipsdefinitionRelationship:textboxtherelationshipispresentedintheformIntheparententityR/1childentity.在這段關(guān)系的關(guān)系:文本框的形式給出了R/1孩子家長實(shí)體的實(shí)體TheVerbPhraseportionofthisboxallowsustodefinethelabeltoplaceontherelationshipinplaceofR/1.這個(gè)動(dòng)詞短語的一部分,這盒允許我們來定義標(biāo)簽的地方的關(guān)系上所處的R/1SincetheparententityisPropertyandtheChildentityisInspection,theParent-to-Childverbphrasewillread"PropertyUndergoesInspection."自從父母實(shí)體是財(cái)產(chǎn)和孩子的主體是檢查、Parent-to-Child動(dòng)詞短語會(huì)讀"財(cái)產(chǎn)經(jīng)歷檢查?！盩heChild-to-Parentverbphrasewillread"InspectionUndertakenatProperty."動(dòng)詞短語的Child-to-Parent會(huì)讀”的檢測在進(jìn)行財(cái)產(chǎn)?！盜ntheRelationshipCardinalityportionofthiswindow,wecandeterminehowmanychildentityoccurencesmaybeassociatedwitheachparententityoccurence.人際關(guān)系的行集數(shù)的一部分,這窗戶,我們可以決定了有多少孩子實(shí)體檢測儀可伴有每個(gè)父母實(shí)體發(fā)生Morespecifically,"OnePropertyUndergoesZero,OneorMoreInspections."更具體地說,“一個(gè)財(cái)產(chǎn)經(jīng)歷零,一個(gè)或更多的檢查?！盢oticethatatthispointwearealsoabletodefineparticipation.值得注意的是,在這一點(diǎn)上我們也能夠定義的參與。Ifeachpropertyhadtohaveundergoneatleastoneinspectioninordertobemandatoryparticipationstoredinthedatabase,thenwecouldhaveforcedbychoosingtheOneorMoreoption.如果每個(gè)財(cái)產(chǎn)不得不經(jīng)歷了至少一個(gè)檢測為了被儲(chǔ)存在數(shù)據(jù)庫中,那么,我們就可以迫使強(qiáng)制性參與挑選一個(gè)或更多的選擇。ClickOKtocompletetherelationshipdefinition,asshowninFigure12.點(diǎn)擊OK完成關(guān)系定義,如圖12。Figure12:FinishedrelationshipNoticethatwhenanentityparticipatesasthechildinanidentifyingrelationshipitismodeledwithroundedcorners.值得注意的是,當(dāng)一個(gè)實(shí)體作為識別的關(guān)系那孩子是模仿和圓角。Thisnotationisusedforwhatinotherdatamodelingtoolsiscalleda"WeakEntity".這個(gè)符號是用來在其他數(shù)據(jù)建模工具,一種被稱為“弱單位”。TherelationshipbetweenInspectionandEmployeeissomewhatdifferent.檢查和員工之間的關(guān)系是有不同的。Itisaone-to-manyrelationship,butnon-identifying,becausetheprimarykeyofEmployeeisnotitispartoftheprimarykeyofInspection.這是一個(gè)一對多的關(guān)系,但它是non-identifying中的主鍵,因?yàn)楣蛦T沒有部分的主鍵檢查Forsucharelationship,wemustclickonthenon-identifyingrelationshipicon(),whichusesadashedlineinsteadofasolidline.對于這樣一個(gè)關(guān)系,我們必須點(diǎn)擊屏幕上的圖標(biāo)()),它使用一個(gè)虛線來代替一個(gè)實(shí)線。Asbefore,weclickontheicon,thentheparententity,thenthechildentity.和以前一樣,我們點(diǎn)擊這個(gè)圖標(biāo),那么父的實(shí)體,然后孩子的實(shí)體Clickonthenon-identifyingrelationshipicon,thentheEmployeeentity,thentheInspectionentity.點(diǎn)擊屏幕上的圖標(biāo),然后non-identifying員工關(guān)系實(shí)體,然后檢驗(yàn)實(shí)體Double-clickontherelationshiptobringuptherelationshipdefinitionwindowandfillitinasshowninFigure13.ouble-click的關(guān)系來定義窗口和關(guān)系把它填上如圖13歲。Figure13:Non-identifyingrelationshipdefinition.Asbefore,weprovidemoremeaningfulverbphrasesfortherelationship.和以前一樣,我們提供更多的有意義的動(dòng)詞短語的關(guān)系A(chǔ)sbefore,sinceeachemployeemaybeassociatedwithzero,oneormoreinspections,wechoosethecorrespondingcardinality.和以前一樣,因?yàn)槊總€(gè)員工可能伴有零,一個(gè)或多個(gè)檢查,我們選擇相應(yīng)的行集數(shù)Unlikebefore,whenwechosetheidentifyingrelationshiptype,wehavenowchosenthenon-identifyingrelationshiptype.不同于以往的,當(dāng)我們選擇了識別關(guān)系類型,我們現(xiàn)在已經(jīng)選好了non-identifying關(guān)系類型。Wehavetheoptionofindicatingwhethernullsarepermittedornot.我們可以選擇是否允許nulls表示。Thisdecisionregardstheparticipationoftheparententityinarelationshipwiththechildentity.這一決定將參與實(shí)體的父母與孩子的關(guān)系實(shí)體。Inhavetobeotherwords,doeseachchildentityoccurence(Inspection)associatedwithaparententityoccurence(Employee)?換句話說,每一個(gè)孩子的實(shí)體(檢查)發(fā)生有助于家長實(shí)體發(fā)生(雇員)嗎?Inthiscase,theansweryes.Eachinspectionmustbecarriedoutbyanemployee,oritisnotconsideredaproperinspection.在這種情況下,答案是的。每項(xiàng)考核必須執(zhí)行一個(gè)雇員,或并不被認(rèn)為是一個(gè)適當(dāng)?shù)臋z驗(yàn)。TheparticipationofEmployeeintherelationshipis制性的。mandatory.在參與的員工之間的關(guān)系是強(qiáng)ClickOKtocompletetherelationshipdefinition,asshowninFigure14.點(diǎn)擊OK完成關(guān)系定義,如圖14。Figure14:Non-identifyingrelationshipEmployeeandOfficealsoparticipationinarelationshipwitheachother.員工和辦公室也參與相互認(rèn)識EachEmployeeisassignedtooneandonlyoneOffice,andeachOfficehasoneormoreEmployees.每個(gè)員工被指定到唯一的一間辦公室,每個(gè)辦公室都擁有一個(gè)或更多的員工。Inthisone-to-manyrelationship,OfficeistheparentandEmployeeisthechild.在這一對多的關(guān)系,辦公室是家長和員工是孩子。Sincetheprimarykeyofthechild(Employee)doesnotincludetheprimarykeyoftheparent(Office),thisisanon-identifyingrelationship.自從主鍵的孩子(雇員)并不包括主鍵的父母(辦公室),這是一個(gè)non-identifying關(guān)系。Clickonthenon-identifyingrelationshipicon,Office,andEmployeetocreatethisrelationship.點(diǎn)擊屏幕上的圖標(biāo)non-identifying關(guān)系、寫字樓及員工,形成了這種關(guān)系。Double-clickontherelationshipandfillintherelationshipdefinitionwindowasshowninFigure15.雙擊關(guān)系并填入關(guān)系定義窗口如圖15。Figure15:Anon-identifyingrelationshipwithmandatoryparticipationInFigure15,seeanexampleofarelationshipinwhichparticipationismandatoryforbothentities.在圖15,看一個(gè)例子,這樣一種關(guān)系,參與對雙方都是強(qiáng)制性的實(shí)體TheCardinalityindicatesthateachOfficeisassociatedwithOneorMore(butnotZero)Employees.每間辦公室的行集數(shù)表明,伴隨著一個(gè)或多個(gè)(但不是零)的雇員。TheRelationshipTypeindicatesthatthisisanon-identifyingrelationship,andthatNullsarenotpermitt