University:
California State University, Northridge
Course:
COMP 440 | Database Design
Academic year:

2022
Views:

138

Pages:

4
Author:

folclord7m

Database Design EER Model ER Data Modeling • ER modeling concept is sufficient for representing many database schemas for traditional data processing applications • Additional semantic data modeling is required for complex databases for – CAD/CAM – Telecommunications – Complex s/w systems – Geographic Information System (GIS) EER Model EER Data Modeling • EER model includes all the modeling concepts of the ER model. • In addition, it includes concepts of: – Subclass and superclass – Specialization and generalization – Category or union • These extension makes EER model semantically similar to OO data modeling EER Model Subclass, Superclass, Inheritance • In many cases an entity type has numerous subgroupings of its entities that are meaningful and need to be represented explicitly – E.g. EMPLOYEE entity type may be grouped into SECRETARY, ENGINEER, MANAGER, etc. – Each of these subgroupings is called a subclass of the EMPLOYEE entity type • Every entity that is a member of one of these subclasses is also an employee EER Model