ERwin使用說(shuō)明(中英文)

1、 10/10ERwin使用說(shuō)明(中英文) Getting Started with ER win (Erwin 入門) by Dr. Peter Wolcott Department of Information Systems and Quantitative Analysis College of Information Science and Technology University of Nebraska at Omaha（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） ER win is a popular dat

2、a modeling tool used by a number of major companies in Omaha and throughout the world. （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） The product is currently owned, developed, and marketed by Computer Associates, a leading software developer.（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） The product supports a variety of aspe

3、cts of database design, including data modeling, forward engineering (the creation of a database schema and physical database on the basis of a data model), and reverse engineering (the creation of a data model on the basis of an existing database) for a wide variety of relational DBMS, including Mi

4、crosoft Access, Oracle, DB2, Sybase, and others.該軟件為多種多樣的關(guān)系型數(shù)據(jù)庫(kù)管理系統(tǒng),包括 Microsoft Access,甲骨文,Sybase,DB2,和其他人提供支持?jǐn)?shù)據(jù)庫(kù)設(shè)計(jì)的各個(gè)方面，包括數(shù)據(jù)建模、正向工程（在現(xiàn)有的數(shù)據(jù)模型的基礎(chǔ)上創(chuàng)建數(shù)據(jù)模式和物理數(shù)據(jù)庫(kù)）和逆向工程（在現(xiàn)在的數(shù)據(jù)庫(kù)基礎(chǔ)上創(chuàng)建數(shù)據(jù)模型） This brief tutorial steps you through the process of creating a data model using ER win.（你可以通過(guò)這個(gè)簡(jiǎn)單教程中的步驟運(yùn)用Erwin來(lái)創(chuàng)建數(shù)據(jù)模

5、 型） It will not explain all aspects of ERwin, but will show you the minimum necessary to create and use data models for this class. （這個(gè)課程不可能全面地講解Erwin，但它向你展示了必要的最基本的創(chuàng)建和使用數(shù)據(jù)模型的知識(shí)） It consists of three major segments, which correspond to the project-related assignments in your class: （這個(gè)課程由三個(gè)主要部分組成，它與

6、有關(guān)項(xiàng)目任務(wù)相符） 1.Creation of a basic data model (Conceptual data model) 創(chuàng)建一個(gè) 基本的數(shù)據(jù)模型(概念數(shù)據(jù)模型) 2.Creation of a database schema 建立數(shù)據(jù)庫(kù)模式 3.Creation of the database創(chuàng)建數(shù)據(jù)庫(kù) This tutorial is a static one, suitable for printing.本教程是一個(gè)靜態(tài)的,適合印刷A tutorial using screen captures and narration is also available. 一個(gè)指南使用屏

7、幕捕捉和敘述是可用的。 Section 1. Creation of a basic data model You will be creating a data model similar to that created for the Heartland Properties case study used in class.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 The Entities involved in this model include: Employee, Office, Property, and Inspection. 參與本次的實(shí)體模型包括:員工、辦公、財(cái)

8、產(chǎn)、及檢驗(yàn)。 First, invoke ER win from Start-Programs-Computer Associates-All Fusion- ERwin Data Modeler- Erwin首先，從開始程序CA所 有程序ERwin Data Modeler You will first encounter a dialog box entitled ModelMart Connection Manager（經(jīng)理ModelMart連接）. Simply click on Cancel.將首先遇到一 個(gè)對(duì)話框題為“ModelMart Connection Manager”。只需

9、點(diǎn)擊“取消”。You will be asked to choose between creating a new model, and opening an existing model, as shown in Figure 1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. For this exercise, create a new model.通過(guò)這個(gè)練習(xí),創(chuàng)建一個(gè)新的模型 Figure 1: Create a new model The next dialog box, shown in Figure 2, will ask you to choose

10、 the template to be used to create the new model. 下一個(gè)對(duì)話框,如圖2所示,會(huì)讓你選擇的模板可以被用來(lái)創(chuàng)造新的模型 At this point, you may associate the model with a target DBMS product, such as Microsoft Access, Oracle, DB2, etc. 在這一點(diǎn)上,你可以把這個(gè)模型與如Microsoft Access,甲骨文,DB2等目標(biāo)數(shù)據(jù)庫(kù)產(chǎn)品聯(lián)系在一起 You will have the opportunity to change this cho

11、ice later, but for now choose Microsoft Access. 你之后將有機(jī)會(huì)改變這種選擇,但是現(xiàn)在選擇Microsoft Access。 Also, choose Logical/Physical as the new model type.同時(shí),選擇的邏輯或者物理作為新模型形式 This choice will allow us to switch back and forth easily between a logical model (ER Diagram) and a physical model (database schema). 這個(gè)選擇將讓我

12、們輕易之間來(lái)回切換邏輯模型(ER圖)和物理模型(資料庫(kù)) Figure 2: Selecting a model type ERwin will now display the main window from which most of your ER diagram development will be done, as shown in Figure 3. ERwin現(xiàn)在將顯示在主窗口大部分你ER圖發(fā)展來(lái)完成,如圖3。 Figure 3: The ERwin Workplace ERwin工作場(chǎng)所 The ERwin workplace consists of two main par

13、ts. On the left is the Model Navigator, which displays a hierarchy of items of importance, such as entities, domains, and subject areas. 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。 On the right is the Display Window, which will show the ER diagram itself. 右邊是顯示窗口,它能夠顯示ER圖本身 As you create objects, they will a

14、ppear in the display window (if they are visual in nature, like entities), and appear in the hierarchy within the Model Navigator.當(dāng)你創(chuàng)建對(duì)象時(shí),他們將會(huì)出現(xiàn)在顯示器窗口(如果它們是視覺(jué)的自然屬性,就像實(shí)體),并將出現(xiàn)在層級(jí)模型導(dǎo)航器。 Setting Preferences 偏好設(shè)置 A tool like ER win can accomodate a number of data modeling notations and conventions. 像ER這

15、樣工具可以容納大量的數(shù)據(jù)建模的符號(hào)和對(duì)話 In my class please make the following changes to the preferences before you begin to create your model在我的課上請(qǐng)完成下面的改變的偏好,在你開始之前,創(chuàng)造你的模型: 1.From the Format-Entity Display menu, make sure that Primary Key Designator is checked從格式- 實(shí)體顯示菜單,確保主鍵欄進(jìn)行檢查 2.From the Format-Entity Display men

16、u, make sure that Foreign Key Designator (FK) is un checked.從格式- 實(shí)體顯示菜單,確保外國(guó)關(guān)鍵指示器(FK)是不能檢查 3.From the Format-Entity Display menu, make sure that Show Migrated Attributes is un checked.從格式- 實(shí)體顯示菜單,確保顯示屬性遷移 到un checked 4.From the Format-Relationship Display, make sure that Verb Phrase is checked. 從格式-

17、 關(guān)系顯示、確保動(dòng)詞短語(yǔ)進(jìn)行檢查 In addition, you may choose between two different E-R diagramming notations. 另外,你可以選擇兩種不同的e - r種畫圖符號(hào)In ERwin, click on Model-Model Properties to see the window shown in Figure 3b:點(diǎn)擊模型- 窗口模型屬性看到如圖3b. Figure 3b: Choice of notation This tutorial is based on the Information Engineering

18、(Crows Foot) notation. You may also use IDEF1X, if you wish.本教程是基于信息工程(“烏鴉腳”)的符號(hào)。你也可以使用IDEF1X,如果你愿意的話。 Creating an Entity創(chuàng)造一個(gè)實(shí)體 To create a new entity, click on the entity icon () on the toolbar, or right-click on the word Entity in the Model Navigator. 創(chuàng)建一個(gè)新的 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 If

19、 you click on the entity icon, you then should click on the Display Window where you would like the entity to appear, as shown in Figure 4. 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 Figure 4: A new entity Notice that the default name for the entity is E/x, where x is some number (2 in this cas

20、e). 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) Click on the Tab key several times and notice what happens.點(diǎn)擊Tab鍵了好幾次,通知會(huì)發(fā)生些什么 Pressing the tab key cause the focus to cycle between the three main parts of the Entity: 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 the name of the entity, the primary key attribute(s)主要的關(guān)鍵屬性,

21、and the non-primary key attribute(s)時(shí)速的關(guān)鍵屬性(s). In general, to modify one of these three parts of the entity, you will press the Tab key to cycle to the appropriate part of the entity, then type to add or modify that part of the entity.一般來(lái)說(shuō),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 Right now, pr

22、ess the Tab key until the entity name is highlighted.現(xiàn)在,按Tab鍵,直到實(shí)體名稱是突出了 Then type EMPLOYEE, as shown in Figure 5. 然后輸入雇員,如圖5。 Figure 5: Changing the name of the entity At this point, you may wish to save and name your diagram to avoid loss should the system or application crash. 在這一點(diǎn)上,你可能想要存起來(lái),說(shuō)出你的

23、圖來(lái)避免損失應(yīng)該系統(tǒng)或應(yīng)用程序崩潰。 Adding primary key columns添加主鍵字段 Once you have changed the name to EMPLOYEE, press the Tab key again to move the focus to the next part of the Entity, adding a primary key attribute. 一旦你已經(jīng)更改了名稱給員工,按Tab鍵來(lái)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 Then type the name of the primary key attribute, Emp_Num

24、, as shown in Figure 6. 然后輸入名稱的屬性,Emp_Num主鍵,如圖6。 Figure 6: Adding a primary key attribute Notice that because of the preferences you set earlier, the primary key attribute has a key icon next to it. 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。Press the Tab key one more time to bring the focus below the hor

25、izontal line in the Entity, where you will add in a number of non-primary key attributes.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。 Type Emp_Fname, as shown in Figure 7.Emp_Fname型,如圖7 When you have typed Emp_Name, press the Enter key (not Tab)當(dāng)你打了Emp_Name,按回車鍵(不是選項(xiàng) 卡). Notice what happens當(dāng)你學(xué)得. The cur

26、sor is now positioned for you to add another attribute in this same portion of the Entity, the non-primary key attribute portion. 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。 Figure 7: Adding non-primary key attributes Continue adding the following non-primary key attributes: 繼續(xù)增加下列時(shí)速關(guān)鍵屬性: Emp_Lname Emp_SSN E

27、mp_Street Emp_City Emp_State Emp_Zipcode Emp_Phone Emp_Fax Your diagram should now look like Figure 8. Figure 8: The Employee entity Repeat the entity creation process for the entities and attributes listed in Table 1. 重復(fù)這個(gè)實(shí)體創(chuàng)建過(guò)程中為實(shí)體及其屬性列于表1。 Notice that some of the entities have no primary key attr

28、ibutes (Manager, Associate), and one entity has an attribute which is part of the primary key, but by itself does not constitute a primary key (Inspection). 注意到一些實(shí)體屬性沒(méi)有主鍵(經(jīng)理、副),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))。As we add relationships to the diagram, the nature of the keys for these entities will

29、become clear.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 For the time being, be sure that there are no primary key attributes for Manager and Associate, and only one primary key attribute for Inspection, as shown in Figure 9. 隨著時(shí)間的推移,要確保沒(méi)有關(guān)鍵屬性對(duì)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 Figure 9: Heartland Properties Entities Creat

30、ing Relationships建立人際關(guān)系 ER win supports the creation of relationships with three basic kinds of connectivity （ER win支持創(chuàng)造之間的關(guān)系三種基本的連通性: one-to-one, one-to-many, and many-to-many. Within the one-to-many category, ER win allows us to distinguish between identifying and non-identifying one-to-many relat

31、ionships.這一對(duì)范疇,ithin歐文允許我們區(qū)分識(shí)別和 non-identifying一對(duì)多的關(guān)系。 One-to-many Relationships Well begin with two relationships, between Inspection and Employee and between Inspection and Property.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 Inspection is related to both Property and Employee in one to many relationships. 同時(shí)與

32、檢驗(yàn)是財(cái)產(chǎn)和員工在一對(duì)多的關(guān) 系 Each Inspection is undertaken at one Property; 在進(jìn)行每個(gè)檢查是一套房產(chǎn)each Property may undergo many inspections每處房產(chǎn),可能經(jīng)過(guò)許多檢查. Each Inspection is carried out by one Employee每次檢驗(yàn)進(jìn)行了一名員工; each Employee carries out many Inspections每一位員工進(jìn)行許多檢查. Are these relationships identifying relationships or

33、non-identifying relationships? 這些是關(guān)系識(shí)別關(guān)系或non-identifying關(guān)系嗎? Are these relationships identifying relationships or non-identifying relationships? 這些是關(guān)系識(shí)別關(guān)系或non-identifying關(guān)系嗎? The issue hinges on the nature of the primary key of Inspection, the entity on the many side of the relationship. 問(wèn)題的關(guān)鍵在于性質(zhì)的主

34、鍵的檢驗(yàn)、實(shí)體上的“許多”方面的關(guān)系。 The primary key of Inspection in this example is a composite primary key consisting of two attributes 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 The business rule in effect here is that each property has at most one inspection per day Insp_Date Prop_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)

35、人檢查每天. One might argue whether or not that is a sound assumption, but lets suppose for the sake of illustration that it is. 一個(gè)人可能會(huì)爭(zhēng)辯說(shuō)不管那是一種合理的假設(shè),但為了說(shuō)明我們可以假設(shè)它是。 Notice that the primary key of Inspection includes the primary key of Property, the entity with which it has a relationship.值得注意的是,主鍵檢查包括主鍵的

36、性質(zhì)、實(shí)體與它有關(guān)系 For this reason, we say that the relationship between Inspection and Property is an identifying one-to-many relationship. 因?yàn)檫@個(gè)原因,我們說(shuō),檢驗(yàn)和財(cái)產(chǎn)之間的關(guān)系是一種識(shí)別一對(duì)多的關(guān)系。 An identifying relationship is created by clicking first on the identifying relationship icon ().創(chuàng)建一個(gè)識(shí)別關(guān)系是通過(guò)點(diǎn)擊第一的 在識(shí)別關(guān)系圖標(biāo)() Notice th

37、at it has the crows foot notation (indicating many) and a solid line (indicating identifying). 值得注意的是,它有烏鴉腳的符號(hào)(表示“許多”)和一個(gè)實(shí)線(指著識(shí)別) To create an identifying relationship, click first on this icon, then click on the parent entity (on the one side of the relationship) and then click on the child entity

38、(on the many side of the relationship). 創(chuàng)建一個(gè)識(shí)別關(guān)系,點(diǎn)擊先在這個(gè)圖標(biāo),然后點(diǎn)擊“家長(zhǎng)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) In this case, you will click first on the identifying relationship icon, then on Property, then on Inspection. 在這種情況下,你就會(huì)點(diǎn)擊圖標(biāo)先識(shí)別,然后在產(chǎn)權(quán)關(guān)系,然后在檢查 The results are shown in Figure 10. 結(jié)果顯示于圖10 Figure 10: An ide

39、ntifying relationship Notice that ER win has provided a label R/1 for the relationship, which is not very helpful. 值得注意的是, ER win已經(jīng)提供了一個(gè)標(biāo)簽 R / 1”的關(guān)系,而不是很有幫助 Double-click on the relationship itself to bring up a dialog box in which we can further refine the relationship definition 雙擊關(guān)系本身造就了一個(gè)對(duì)話框,以這種方

40、式我們能夠進(jìn)一步提煉的關(guān)系的定義. Fill out this dialog box as shown in Figure 11. 填寫這對(duì)話框如圖11分 Figure 11: Relationships definition In the Relationship:text box the relationship is presented in the form parent entity R/1 child entity. 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(zhǎng)實(shí)體的實(shí)體 The Verb Phrase portion of this box allows us to d

41、efine the label to place on the relationship in place of R/1. 這個(gè)動(dòng)詞短語(yǔ)的一部分,這盒允許我們來(lái)定義標(biāo)簽的地方的關(guān)系上所處的R / 1 Since the parent entity is Property and the Child entity is Inspection, the Parent-to-Child verb phrase will read Property Undergoes Inspection.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(yǔ)會(huì)讀財(cái)產(chǎn)經(jīng)歷檢查?！?The Chi

42、ld-to-Parent verb phrase will read Inspection Undertaken at Property. 動(dòng)詞短語(yǔ)的Child-to-Parent會(huì)讀”的檢測(cè)在進(jìn)行財(cái)產(chǎn)。” In the Relationship Cardinality portion of this window, we can determine how many child entity occurences may be associated with each parent entity occurence. 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(cè)儀可伴有

43、每個(gè)父母實(shí)體發(fā)生 More specifically, One Property Undergoes Zero, One or More Inspections. 更具體地說(shuō),“一個(gè)財(cái)產(chǎn)經(jīng)歷零,一個(gè)或更多的檢查。” Notice that at this point we are also able to define participation. 值得注意的是,在這一點(diǎn)上我們也能夠定義的參與。 If each property had to have undergone at least one inspection in order to be stored in the database

44、, then we could have forced mandatory participation by choosing the One or More option.如果每個(gè)財(cái)產(chǎn)不得不經(jīng)歷了至少一個(gè)檢測(cè)為了被儲(chǔ)存在數(shù)據(jù)庫(kù)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。 Click OK to complete the relationship definition, as shown in Figure 12.點(diǎn)擊OK完成關(guān)系定義,如圖12。 Figure 12: Finished relationship Notice that when an entity particip

45、ates as the child in an identifying relationship it is modeled with rounded corners.值得注意的是,當(dāng)一個(gè)實(shí)體作為識(shí)別的關(guān)系那孩子是模仿和圓角。 This notation is used for what in other data modeling tools is called a Weak Entity.這個(gè)符號(hào)是用來(lái)在其他數(shù)據(jù)建模工具,一種被稱為“弱單位”。 The relationship between Inspection and Employee is somewhat different. 檢

46、查和員工之間的關(guān)系是有不同的。 It is a one-to-many relationship, but it is non-identifying, because the primary key of Employee is not part of the primary key of Inspection. 這是一個(gè)一對(duì)多的關(guān)系,但它是 non-identifying中的主鍵,因?yàn)楣蛦T沒(méi)有部分的主鍵檢查 For such a relationship, we must click on the non-identifying relationship icon (), which us

47、es a dashed line instead of a solid line. 對(duì)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(lái)代替一個(gè)實(shí)線。 As before, we click on the icon, then the parent entity, then the child entity. 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 Click on the non-identifying relationship icon, then the Employee entity, then the Inspection entity.點(diǎn)擊屏幕上的

48、圖標(biāo),然后 non-identifying員工關(guān)系實(shí)體,然后檢驗(yàn)實(shí)體 Double-click on the relationship to bring up the relationship definition window and fill it in as shown in Figure 13. ouble-click的關(guān)系來(lái)定義窗口和關(guān)系把它填上如圖13歲。 Figure 13: Non-identifying relationship definition. As before, we provide more meaningful verb phrases for the rel

49、ationship. 和以前一樣,我們提供更多的有意義的動(dòng)詞短語(yǔ)的關(guān)系 As before, since each employee may be associated with zero, one or more inspections, we choose the corresponding cardinality. 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) Unlike before, when we chose the identifying relationship type, we have now chosen the non-identifyin

50、g relationship type. 不同于以往的,當(dāng)我們選擇了識(shí)別關(guān)系類型,我們現(xiàn)在已經(jīng)選好了non-identifying關(guān)系類型。 We have the option of indicating whether nulls are permitted or not. 我們可以選擇是否允許nulls表示。 This decision regards the participation of the parent entity in a relationship with the child entity. 這一決定將參與實(shí)體的父母與孩子的關(guān)系實(shí)體。 In other words, d

51、oes each child entity occurence (Inspection) have to be associated with a parent entity occurence (Employee)? 換句話說(shuō),每一個(gè)孩子的實(shí)體(檢查)發(fā)生有助于家長(zhǎng)實(shí)體發(fā)生(雇員)嗎? In this case, the answer yes. Each inspection must be carried out by an employee, or it is not considered a proper inspection. 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

52、被認(rèn)為是一個(gè)適當(dāng)?shù)臋z驗(yàn)。 The participation of Employee in the relationship is mandatory. 在參與的員工之間的關(guān)系是強(qiáng)制性的。 Click OK to complete the relationship definition, as shown in Figure 14. 點(diǎn)擊OK完成關(guān)系定義,如圖14。 Figure 14: Non-identifying relationship Employee and Office also participation in a relationship with each other.員工

53、和辦公室也參與相互認(rèn)識(shí) Each Employee is assigned to one and only one Office, and each Office has one or more Employees. 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。In this one-to-many relationship, Office is the parent and Employee is the child. 在這一對(duì)多的關(guān)系,辦公室是家長(zhǎng)和員工是孩子。 Since the primary key of the child (Employee) does n

54、ot include the primary key of the parent (Office), this is a non-identifying relationship. 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。 Click on the non-identifying relationship icon, Office, and Employee to create this relationship. 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-click on the

55、 relationship and fill in the relationship definition window as shown in Figure 15.雙擊關(guān)系并填入關(guān)系定義窗口如圖15。 Figure 15: A non-identifying relationship with mandatory participation In Figure 15, see an example of a relationship in which participation is mandatory for both entities. 在圖15,看一個(gè)例子,這樣一種關(guān)系,參與對(duì)雙方都是強(qiáng)制性的實(shí)體 The Cardinality indicates that each Office is associated with One or More (but not Zero) 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。 The Relationship Type indicates that this is a non-identifying relationship, and that Nulls are not permitted.他的關(guān)系類型顯示,這是一個(gè)non-identifying關(guān)系,