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1. The entities Report, Purchase, and Employee could be added. Report consolidates the account details of a customer. It involves recent purchases, coupons history and points summary. Purchase shows a record of what the customer buys. It logs the coupon usage, list of products purchased and the date of purchase. Employee would be the person working for Petrie Electronics and currently monitoring the transactions and services. 2. Coupon- special promotion created for a specific customer. Customer- someone who buys products.
Product- an item made available for sale.
Promotion- a special incentive provided to the customer.
Service- a job performed by one of Petrie’s associates.
Transaction- record that a particular product or service was sold to a specific customer. Purchase- a unique number used to identify a purchase.
Each identifier was chosen for the following reasons:
Must be a noun
Follows a standard format
Similar but distinguishing names
States what the attribute is and why it is important
4. These are drawn in problem 1 in the dia diagram. One-to-many includes customer to coupon, customer to purchase, customer to transaction, product to purchase and employee to transaction. Zero-to-many includes customer to promotion and product to transaction. Customer to report is a one-to-one.
5. The entity Employee does not play an important role in Petrie’s case. It is necessary for an employee to be present to make changes to a transaction. Considering an ER diagram design from a database point of view, the transactions are monitored by the database admin. The absence of this entity does not have any great consequence.
7.Coupon_Expiry_Date, Transaction_Date, Report_Date, Purchase_Date, Promotion_Expiry Date.
Attributes must be kept to keep track of historic time and maintain records for later reference.