EXERCISE 1
•A)
• 1- supertype table with all subtypes and their attributes mapped up into the single
supertype table.
• 2- Subtype tables with properties of the supertype mapped down into each subtype table
• 3- supertype + set of subtype table.
•B)
• Supertype - If the difference between the data stored in both the entities is less, supertype entity
is preferred. This is because of the minimal difference that a subtype cluster can be created.
• Subtype - If the difference in the data stored is more or higher, subtype table is preferred as it will
store the common attributes.
EXERCISE 2
Department
C
project
employee
REL
department
EXERCISE 3
SHIPPING
ORDER
C
LINE ITEMS
REL
SUPPLIERS
PARTS
EXERCISE 4
PARTS
SE+
LARGE PARTS
c
MANY SMALL
PART
•
SMALL PARTS
EXERCISE 5
doctor
Rel f
D
appointment
BILL
patient
C
C
SE
PAYMENT
NO
INSURANCE
SUBSCRIBER
C
C
INSURANCE
COMPANY
EXERCISE 6
•
EQUIPMENT
EQUIPMENT
OWNERSHIP
REL
JOB1
SE
EMPLOYEE
JOB N
C
BENEFITS
DEPARTMENT
D
SE+
JOB
CLASSIFICATION
REF
SUPERVISOR
SUPERVISE
EXERCISE 7
Stevens community
SE+
ISSS
STUDENT
FACULTY
S
SE+
S
STUDENT HEALTH INSURANCE
DUCK CARD
FULL TIME
UG
PART TIME
GRADUATE
EXERCISE 8
• ACTIVITY: purchasing a Car
• INVARIANT:
• The car belongs to owner.
• There is no third party involved.
• PRECONDITION:
• The car is in good condition.
• Its an electric car.
• The buyer makes the payment first and the car is his.
• POSTCONDITION:
• A car technician is there for observation.
• car have insurance for one year.
• Payment is made to the car technician along with contract.
• TRIGGER:
• car is up for sale and within the budget and insurance cover.
Buy a car
Observe the car
Call car technician
Pay technician
Ask for price
negotiate
Pay price to buy car