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f.
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17.7 Model the cardinalities of the following business policies:
a. The relationship between the Sale and Receive Cash events
for installment sales.
b. The relationship between the Sale and Receive Cash events at a convenience
store.
c. The Take Customer Order–Sale relationship in a situation when occasionally
several shipments are required to fill an order because some items were out of
stock.
d. The Sale-Inventory relationship for a custom homebuilder.
e. The relationship between the Sale and Receive Cash events for Dell computers,
which requires customers to pay the entire amount of their purchase in advance,
prior to Dell shipping the merchandise.
f. The relationship between the Sale and Receive Cash events for a retail store that
has some in-store sales paid in full by customers at the time of the sale but that
also makes some in-store sales to customers on credit, billing them later and
permitting them to make installment payments.
Alternate solution assuming all payments are for one and only one sale.
g. The relationship between the Receive Inventory and Disburse Cash events in the
case where suppliers require payment in advance, in full.
h. The relationship between the Call on Customers event (i.e., the visit by a
salesperson to a potential customer) and the Take Customer Order event for a
business that is only conducted door-to-door (e.g., kitchen knives, certain books,
etc.) so that the only way to order the items is when a salesperson visits the
customer. (Hint: do you think every call results in an order?)
i. The relationship between the Call on Customers and Take Customer Orders
events for a manufacturer which also accepts orders on its Web site.
j. The relationship between the Receive Inventory and Disburse Cash events for a
company which receives monthly bills from its suppliers for all purchases made
the previous month; some suppliers require payment of the entire bill, in full,
within 30 days or they will not accept any subsequent orders, but other suppliers
accept installment payments.
17.8 The Computer Warehouse sells computer hardware, software, and supplies (such as
paper). Individual customers just walk into the store, select merchandise, and must
pay for their purchases in full before leaving the store. Corporate customers,
however, call in orders in advance, so that the items are waiting to be picked up.
Corporate customers may charge their purchases to their account. The Computer
Warehouse mails corporate customers monthly statements that summarize all
purchases made the prior month. Corporate customers pay the entire balance, as
listed on the monthly statement, with one check or EFT transaction.
Draw an REA Diagram for Computer Warehouse revenue cycle, complete with
cardinalities.
17.9 The Computer Warehouse purchases its inventory from more than a dozen different
vendors. Orders are placed via telephone, fax, or on the supplier’s Web site. Most
orders are delivered the next day. Most orders are filled completely in one shipment,
but sometimes a supplier is out of stock of a particular item. In such situations, the
bulk of the order is shipped immediately and the out-of-stock item is shipped
separately as soon as it arrives (such shipments of back orders are never combined
with any new orders placed by the Computer Warehouse). The Computer
Warehouse pays for some of its purchases COD but usually pays by the 10th of the
month for all purchases made the prior month. None of its suppliers allows it to
make installment payments.
Draw an REA Diagram for Computer Warehouse expenditure cycle, complete with
cardinalities.
17.10 Stan’s Southern Barbeque Supply Store orders mass-produced barbecue products
from various suppliers. Stan’s maintains information about a contact person at each
supplier along with all required address information. Each purchase order has the
order number, date, tax, and total. Purchase orders also contain the following
information for each product ordered: stock number, description, and price. The
manager of Stan’s places orders by fax several times a day, whenever he notices that
an item is running low. Some suppliers fill each individual order separately. Others,
however, consolidate orders and fill all of them in one weekly delivery. Stan's
suppliers never make partial shipments; if they are out of stock of a certain item,
they wait until they obtain that item and then ship the entire order. Some suppliers
require payment at the time of delivery, but others send Stan’s a monthly statement
detailing all purchases during the current period. Two suppliers allow Stan’s to
make installment payments for any individual purchase orders that exceed $20,000.
Draw an REA Diagram for Stan’s Southern Barbecue expenditure cycle, complete
with cardinalities
SUGGESTED ANSWERS TO THE CASES
17.1 Sparky’s Amusement Park is an entertainment park run by recent college
graduates. It caters to young people and others who are young at heart. The owners
are very interested in applying what they have learned in their information systems
and marketing classes to operate a park better than any other in the area. To
accomplish these goals, guests of the park are given a personal “membership card”
as they enter. This card will be used to identify each guest. Assume that a new card
is issued each time a guest comes to the park. As a result, the system does not have to
track one person over a period of time. As at other parks, guests pay a flat fee for
the day and then are able to ride all of the attractions (such as a double-looping
roller coaster and the merry-go-round) for no extra charge. The owners, however,
want to track the rides each guest takes and the attractions the guests use. They plan
to have guests swipe their membership card through a computerized card reader,
which automatically enters information into the computer system. This should allow
the owners to gather data about the following:
Number of people who use each piece of equipment. (How many people rode the
Ferris wheel today?)
Number of times each piece of equipment is operated daily.
Times of day the attraction is busy or slow. (When was the carousel the busiest?)
Number of attractions each guest uses. (How many different pieces of equipment
did customer 1122 ride?)
Number of rides each guest enjoys. (How many different rides did customer 1122
enjoy? Did each guest go on any rides more than once?)
Draw an REA diagram for Sparky’s revenue cycle only. Be sure to include
cardinalities. State any assumptions you had to make.
(This problem is adapted from one developed for classroom use by Dr. Julie Smith David at Arizona
State University.)
The relationships of interest are those shown in the REA diagram. Most cardinalities are
standard, except for the following:
The “Give Ride” event involves running one particular piece of equipment. This
solution assumes that attractions are run (e.g., the Ferris Wheel is turned on) at
regular intervals, even if no customers happen to be on it. If, however, an attraction is
