Broadway Entertainment Co., Inc. Case Question Solutions 1. Review the data flow diagrams you developed for questions in the BEC case at the end of Chapter 5 (or diagrams given to you by your instructor.) Study the data flows and data stores on these diagrams and decide if you agree with the team’s conclusion that there are only the six entity types listed in this case and in BEC Figure 6-1. If you disagree, define additional entity types, explain why they are necessary, and modify BEC Figure 6-1.
The six entity types in BEC Figure 1 are the only ones needed to represent the MyBroadway system. However, depending on what data about Customers and Employees are required, entities for these objects may also be required. 2.
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Request ID is the identifier of the entity Request because a customer could make more than one request for a product on a certain day. Sale ID and Rental ID are the identifiers of the entities Sale and Rental, respectively, because a customer could buy or rent more than one product on a certain day. 4. Using your answer to Question 3, draw the relationships between entity types needed by the system. Remember, a relationship is needed only if the system wants data about associated entity instances. Give a meaningful name to each relationship. Specify cardinalities for each relationship and explain how you decided on each minimum and maximum cardinality on each end of each relationship. State any assumptions you made if the BEC cases you have read so far and the answers to questions in these cases do not provide the evidence to justify the cardinalities you choose. Redraw your final E-R diagram in Microsoft Visio.
The relationships between Product and Comment, Pick, Request, Rental, and Sale are all one-to-many relationships. A Product may have zero or many Comments, Picks, Rentals, and Sales associated with it. Comments, Picks, Requests, Rentals, and Sales must have one and only one Product associated with them. Requests may not have a Product associated with them (until the product goes into inventory). A suggested ERD is provided at the end of