7-54. What date-related attributes did you identify in each of the entity types in your answer to Case Question 7-51? Why are each of these needed? Can you make some observations about why date attributes must be kept in a database, based on your analysis of this databaseEntity: Short name, name, plural, volume (initial, maximum, average, growth rate), datawarehouse type, list of attributes, descriptionAttributes: Primary UID, optional?, the percentage used (initial, average), domain, type,maximum length, average length, decimal places, units, derivation, on condition, nullvalue, default, sequence in sort, sort order.Relationships: From entity name, from relationship name, from optionality and degree toentity name, to relationship name, to optionality and degree, description PE TABLE 7-1:Entity Descriptions for the Preliminary E-R Diagram for Petrie's Customer Loyalty SystemEntityDescriptionCouponA coupon is a special promotion created specifically for an individual customer. A coupon is for a set dollar amount, for example, $10. The customer may use it like cash or like a dollars-off promotion when purchasing products or services.Coupons can only be created for an individual customer based on the points in his or her customer loyalty account. For each dollar value of a coupon, a certain number of points must be redeemed. Coupons must be accounted for whencreated and when redeemed.CustomerA customer is someone who buys products and/or services from Petrie's Electronics. Customers include both online customers and those who shop in Petrie's brick-and-mortar stores.ProductAn item made available for sale to a Petrie's customer. For example, a product is a 40" Sony LCD HD television. Products can be purchased online or in brick-and-mortar stores.PromotionA promotion is a special incentive provided to a customer to entice the customer into buying a specific product or service. For example, a promotion intended to sell Blu-ray disks may involve 2-for-1 coupons. Promotions are targeted to allcustomers, or to subsets of customers, not just to individual customers.ServiceA job performed by one of Petrie's associates for a customer. For example, upgrading the memory in a computer by installing new memory cards is a service that Petrie's provides for a fee. Services may only be ordered and performed inbrick-and-mortar stores, not online.TransactionA record that a particular product or service was sold to a specified customer on a particular date. A transaction may involve more than one product or service, and it may involve more than one of a particular kind of product or service. Forexample, one transaction may involve blank DVDS and prerecorded DVDS, and the prerecorded DVDS may all be of the same movie. For members of the loyalty program, each transaction is worth a number of points, depending on the dollarvalue of the transaction.Alternative BAlternative A SBSIRatingNovaScoreCriteriaWeightXRAAlternativeRatingScoreRatingScoreRequirementsEffective customer15incentivesEasy for customers754.604601010to use33040550Proven performanceEasy to implementScalableVendor support405033015420315361030403030103040360220250215Constraints45307540Cost to buyCost to operateTime to implementStaff to implement1536034410404315153151033043304015540120160Total100340405375PE FIGURE 7-2Evaluation matrix for customer loyalty proposals."Yes, but just barely," Sanjay said. “There is only a five-point difference between XRA and Nova, so they are pretty comparable when it comes to constraints. But I think the XRA system has a pretty clear advantage in meeting our requirements.""XRA seems to be pretty highly rated in your matrix in terms of all of the requirements. You have XRA ranked better than the other two proposals for implementation, scalability, and vendor support," Jim said. “The '5' you gave XRA for proven performance isone of the few '5s' you have in your whole matrix.""That's because XRA is one of the best companies in the industry to work with," Sanjay responded, "The company's reputation is stellar.""This looks really promising," Jim said. "Let's see if reality matches what we have here. It's time to put together the formal request for proposal. I'll get that work started today. I hope that all three of these companies decide to bid." Structuring Systems Requirements: Conceptual Data ModelingJim Watanabe, manager of the "No Customer Escapes" project and assistant director of IT for Petrie's Electronics, was sitting in the company cafeteria. He had just finished his house salad and was about to go back to his office when Stephanie Welch satdown at his table. Jim had met Stephanie once, back when he started work at Petrie's. He remembered she worked for the database administrator."Hi, Jim, remember me?" she asked."Sure, Stephanie, how are you? How are things in database land?""Can't complain. Sanjay asked me to talk to you about the database needs for your new customer loyalty system." Stephanie's phone binged. She pulled it out of her oversize bag and looked at it. She started to text as she continued to talk to Jim. “How faralong are you on your database requirements?"That's kinda rude, Jim thought. Oh well. "We are still in the early stages. I can send you a very preliminary E-R diagram we have [PE Figure 7-1 D), along with a description of the major entities."CouponServicePromotionCustomerTransactionProductPE FIGURE 7-1Initial E-R for Petrie's customer loyalty program."OK, that will help. I suspect that you won't have too many new entities to add to what's already in the system," Stephanie responded, still looking at her phone and still texting. She briefly looked up at Jim and smiled slightly before going back to texting."Just send the E-R to me, and l'll let you know if I have any questions." She stood up, still looking at her phone. "Gotta go," she said, and she walked away.OK, Jim thought, I need to remember to send Stephanie the preliminary E-R we have. I should probably send her the entity descriptions too (PE Table 7-1 L), just in case. Jim stood up, carried his tray over to the recycling area of the cafeteria, and went backto his office.When Jim got back to his office, Sanjay was waiting for him."I've got more information on those alternatives we talked about earlier," Sanjay said. "I had one of my employees gather some data on how the alternatives might satisfy our needs." (See the descriptions of the alternatives in PE Table 5-2 D.) Sanjay handedJim a short report. "The matrix shows the requirements and constraints for each alternative and makes it relatively easy to compare them." (See PE Figure 7-2 D.)"The matrix favors the XRA CRM system," Jim said, after looking over the report. "It looks like their proposal meets our requirements the best, but the Nova group's proposal does the best job with the constraints."

Answered: 54. What date-related attributes did…

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7-54. What date-related attributes did you identify in each of the entity types in your answer to Case Question 7-51? Why are each of these needed? Can you make some observations about why date attributes must be kept in a database, based on your analysis of this database

Entity: Short name, name, plural, volume (initial, maximum, average, growth rate), data

warehouse type, list of attributes, description
Attributes: Primary UID, optional?, the percentage used (initial, average), domain, type,

maximum length, average length, decimal places, units, derivation, on condition, null

value, default, sequence in sort, sort order.
Relationships: From entity name, from relationship name, from optionality and degree to

entity name, to relationship name, to optionality and degree, description

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Date related attributes

The date related attributes are those that are capable of storing the details of day, month, and year as a single value. In some cases, these are also called as composite attributes. For instance, the Date_of_Birth of a student in an Entity Student is a date related attribute.