CS 3630 Database Design and Implementation

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

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

Problems with E-R Model Chasm Traps Staff Branch PropertyForRent Has Oversees 1..1 1..* 0..1 0..* The relationship between PropertyForRent and Branch may be missing.

Problems with E-R Model Correcting Chasm Traps One extra relationship is needed Staff Branch PropertyForRent Has Oversees 1..1 1..* 0..1 0..* Offers 1..1 1..*

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

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

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

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

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

Participation: Mandatory SuperClass: Staff SubClasses PartTime FullTime

Participation: Optional SuperClass: Staff SubClasses Supervisor Supervisee

Disjoint (Xor) SuperClass: Staff SubClasses PartTime FullTime

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

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

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

Assignment3 EER not required.