PROBLEMS
1. REA DIAGRAMS
The three differences between REA diagrams and ER diagrams:
1) Entities on REA diagrams are divided into three classes (Resources,
Events, and Agents) and organized into constellations by class on the
2) ER diagrams present a static picture of the underlying business
phenomena. Relationships between data are shown through cardinality and
associations, but the sequence of activities that determine the cardinality and
3) The third difference between ER and REA diagrams pertains to naming
conventions for entities. In ER diagrams, entity names are always
represented in the singular noun form. REA modeling applies this rule when
2. REA ASSOCIATIONS
B is the correct association. Each Sell Auto event could involve one or
3. REA ASSOCIATIONS
The proper association is “C”. Each cash receipt is for only one Sell Auto
event and each Sell Auto event requires one immediate payment in full.
4. REA ASSOCIATIONS
Chapter 1 Page 2
5. REA MODEL EXTRACT
Resources Events Agents
Raw
Material
Invento
ryy
Pick
Inventory
Warehouse
Clerk
Finished
Goods
invent
ory
Produce
Product
Production
Worker
Causes
Increases
Reduces
Performs
Requests
Chapter 1 Page 3
6. REA MODEL – HORIZON BOOKS
Book
Invento
ry
Take
Order
Custome
r
Sal
es
Cler
k
Reduces
Process Order
Cas
h
Purchases
Related
to
Query
Availability
Review Items
Available
Requests
Receives
Cash
Custome
r
Duality
Remits
Increases
Chapter 1 Page 4
7. REA MODEL – FEINMAN COMPUTERS
ANSWER A and B:
Inventory Take Order
Customer
Sales Clerk
Reserves
Process Order
Increases Receive Cash Cash Receipts
Clerk
Shipping Clerk
Cash
Places Order
Processes
Remittance
Ship Product
Causes
Customer
Reduces
Duality
Ships
Remits
Receives
Chapter 1 Page 5
ANSWER C
Table Name Primary Key Foreign Key(s) Attributes
Inventory Item Number Description, Warehouse Location, Quantity on
Hand, Reorder Point, On-Order Quantity, Available
for Sale, Supplier Number, Unit Cost, Retail Price
Cash Account
Number
Take Order
Ship Product
Receive Cash
Invoice Amount, Shipped Date, Due Date, Close
Date,
Invoice
Number
Order Number
Customer Number
Employee Number
Order
Number
Inquiry Number
Customer Number
Employee Number
Order Date, Promised Date, Terms Of Trade,
Remittance
Number
Customer Number
Employee number
Account Number
Customer Check Number, Date, Amount
Balance
Supplier
Customer
Employee
Customer Number
Name, Address, Line of credit, Available Credit,
Current Balance, Last Payment Date,
Employee Number SSN, Name, Address, Date of Birth, Job Title,
Data Hired, Pay Rate, Vacation Time Accrued
Supplier Number Name, Address, Terms of Trade, Vendor lead time,
Carrier used, On-time delivery record, Incomplete
shipments record, Damaged shipments record,
Price disputes record
Table
Name
Inventory-Ord
er Link
Inventory-Shi
p Link
Primary Key Attributes
Item Number
Order Number
Quantity Ordered
Item Number
Invoice Number Quantity Shipped, Actual Price
Linking Tables
Tables, Keys, and Attributes for Feinman Computers
Chapter 1 Page 6
8. REA MODEL – K CANNON, INC
ANSWER A and B:
Inventory Order Product Purchasing
Clerk
Supplier
Receive Product
Disburse
Cash
Cash
Cash
Disburseme
nt
Clerk
Supplier
Receiving
Clerk
Processes
Flags Item
Increases
Causes
Duality
Receives
Ships
Prepares
Receives
Processes
Decreases
Chapter 1 Page 7
ANSWER C.
Tables, Keys, and Attributes for K Cannon Inc.
Table Name Primary Key Foreign Key(s) Attributes
Receive Product
Order Product Purchase Order
Number
Number
Employee
Number
Expected Total Price
Supplier Number
Employee Number
Date Received, Carrier, Total Amount Due, Due
n Link
Receiving Report
Number
Chapter 1 Page 8
9. REA MODEL -PAYROLL SYSTEM
ANSWER A and B:
NOTE: The task of preparing the payroll register described in the case is not an REA event and
9. Tables, Keys, and Attributes
Chapter 1 Page 9
10. REA MODEL – FIXED ASSET SYSTEM
ANSWER A and B:
NOTE: The task of recording depreciation is not an REA event and should not be modeled in an REA
diagram. Depreciation is an accounting technique that arbitrarily allocates some of the cost of the
Chapter 1 Page 10
ANSWER C.
Tables, Keys, and Attributes