1. CS 3630 Database Design and Implementation

2. Problems with E-R Model
Fan Traps
College
Faculty
Department
Has
Operates
The relationship between Faculty and Department is missing.

3. Problems with E-R Model
Correcting Fan Traps
The relationship between College and Faculty is
maintained
Department
College
Faculty
Has
Operates

4. Problems with E-R Model
Chasm Traps
Staff
Branch
PropertyForRent
Has
Oversees * *
The relationship between PropertyForRent and Branch may be missing.

5. Problems with E-R Model
Correcting Chasm Traps
One extra relationship is needed
Staff
Branch
PropertyForRent
Has
Oversees * *
Offers
1..1
1..*

6. EER: Enhanced E-R Model
Specialization / Generalization
SubClass / SuperClass
Not required for Assignment 3

7. Subclasses for Different Roles
SuperClass:
Staff
SubClasses:
Manager
Instructor
SalesPersonnel
Secretary

8. Common and Different Attributes
SuperClass:
Staff: staffNo, name, address, phone, salary
SubClasses:
Manager: mgrStartDate, bonus
SalesPersonnel: salesArea, carAllowance
Secretary: typingSpeed

9. Different Entities for Subclasses?
staffNo
Name
Position
Bonus
salesArea
typingSpeed
SL21
John White
Manager
2000
SG37
Ann Beech
Secretary
100
SA9
Mary Howe
Sales Asst
SA1A

10. Constraints for Sub-Classes
Participation:
Mandatory
Optional
Disjoint:
Disjoint (or)
Non-disjoint (and)
Business Rules

11. Participation: Mandatory
SuperClass:
Staff
SubClasses
PartTime
FullTime

12. Participation: Optional
SuperClass:
Staff
SubClasses
Supervisor
Supervisee

13. Disjoint (Xor)
SuperClass:
Staff
SubClasses
PartTime
FullTime

14. Nondisjoint (And) SuperClass: Staff SubClasses: Manager SalesPersonnel
Secretary

15. EER Diagram Staff staffNo Manager bonus SalesPersonnel salesArea
{Mandatory, And}
Manager
bonus
SalesPersonnel
salesArea
Secretary
typingSpeed

16. EER Diagram Staff staffNo FullTime salaryScale PartTime hoursRate
{Mandatory, Xor}
FullTime
salaryScale
PartTime
hoursRate

17. Assignment3
EER not required.