This binary relationship can be shown separately from, and in addition to, a ternary relationship. Using a similar example of CUSTOMERS, VENDORS, and PRODUCTS, suppose retail vendors and suppliers of products have a special relationship that does not involve customers - such as wholesaling with an entirely different price structure. Just because there is a ternary relationship does not mean that binary relationships among the entities may not exist. N-ary Relationships Do Not Preclude Binary
#Create a ternary diagram full#
PRODUCT: SUPPLIER: CUSTOMER::1:1:1 full participation on all sides. PRODUCT: SUPPLIER: CUSTOMER::1:M:M, partial participation on all sides.Ĭ. PRODUCT: SUPPLIER: CUSTOMER::1:1:1, partial participation on all sides.ī. What situations might create each of the following structural constraints?Ī. Think of some more intersection attributes for the PRODUCT, SUPPLIER, and CUSTOMER ternary example given above.ħ. Using the three entities used above (PRODUCT, SUPPLIER, and CUSTOMER), draw an ER diagram that depicts the following: A supplier must supply many products to many customers at different prices on different dates.Ħ. Using the three entities used above (PRODUCT, SUPPLIER, and CUSTOMER), draw an ER diagram that depicts the following: A customer must buy one and only one product from a supplier at a particular price on a particular date.ĥ. Next we look at the structural constraints of ternary relationships.įigure 7B: Instances of a Ternary Many-to-Many-to-Many for CUSTOMER:PRODUCT:SUPPLIER Relationshipģ. In the case of higher-order relationships, they are most often found by finding an attribute that necessitates the existence of the n-ary relationship. Another intersection attribute (see Figure 7.2) could be date, which could be the date of the sale of a product to a customer by a supplier. Also, for customers, one might assume that some items are bought on sale, some not. For different suppliers, one might also assume different prices for a product at different points in time. This ternary case is more realistic because customers generally pay different prices for the same product by different manufacturers or suppliers. PRODUCT–SUPPLIER–CUSTOMER customerID productID supplierID priceįigure 7.2: An ER Diagram (with Only Primary Keys) Showing a ThreeWay Relationship Some sample data for Figure 7.2 would be: This situation is depicted in Figure 7.2.įigure 7.2 represents the entities PRODUCT, SUPPLIER, and CUSTOMER, and a relationship, buy, among all three entities, shown by a single relationship diamond attached to all three entities. An icon representing the diagram is added to the tree view.Intersection attribute, price. The workspace displays 'Statechart' as a watermark. Point to New and click Statechart Diagram.Ī blank page appears, and the UML Statechart stencil becomes the top-most stencil. In the tree view, right-click the icon representing the class or use case that includes behavior you want to represent in a statechart diagram. On the File menu, point to New, point to Software, and then click UML Model Diagram. Open the UML model that contains the class or use case that includes behavior you want to represent in a statechart diagram. Double-click a transition to label it with a string that, in addition to an event signature, can also include a guard condition, an action expression, and more. The event which triggers the transition is named in the transition string. Transitions indicate that, in response to an event, an object will go from one state to another and perform an action. Double-click a State shape to add a name and list its internal actions and activities. The initial state is the state of an object before any events in the diagram have acted upon it.Ī state represents an instant in the life of an object.
0 kommentar(er)
