Enhanced Entity Relationship Model (Database Management System)

1. ENHANCED E-R MODEL
REF-ID :RD1507A02

2. ENHANCED E-R MODEL
• Specialized Entity relation diagram which is used for modeling the conceptual
database.
• It is used for various concept related to Object Oriented Programming.
• It represent requirements and the complexity of the complex database.
EERD includes:
A)Subclass and Superclass
B)Generalization and Specialization

3. A)SUPER-TYPE AND SUB-TYPE
Subclass or Subtype
• Entity part of super class which
relates one or more subtypes or
subclass
• Eg:- Set of natural positive number
and Set of natural negative number
is subtype of super-type whole
numbers
Superclass or Supertype
• Subgroup of subtype entities.
• Eg:-University is superclass entity and
its sub-type entity is
department(dep_id , dep_no).

4. B)GENERALIZATION AND SPECIALIZATION
Generalization
• Method of creating and defining a
general entity type from collection
of specialized entity type.
• Generalization is “IS_A” relationship
• Generalization is represented with
triangle with a line
Specialization
• Determines subclass of super class
and determines relation between
them.
• In specialization ,categorization is
done according the characteristics
• Top-down Approach where high
level entity is break down into low
level entity

5. PARTICIPATION
• A subclass or subtype is also a member of superclass or super-type.
Types of participation in EERD :
1)Disjoint Mandatory(OR)
2)Disjoint Optional(AND)
3)Overlapping Mandatory(OR)
4)Overlapping Optional(AND)

6. DISJOINT MANDATORY(OR)
Must belong to the member of subclass
 Either the book must be for rent or for sale

7. DISJOINT OPTIONAL
READER
STAFFSTUDENT
 Either the reader is student or staff
Does not have to be a member of subclass

8. OVERLAPPING MANDATORY
• Must be a member of subclass(one or more)
TEACHING STAFF
PG StudentFaculty Lecturer
 Every teaching staff must be faculty lecturer or PG Student.

9. OVERLAPPING OPTIONAL(AND)
• Does not have to belong to member of subclass.
STAFF
Sales
PersonnelBranch Manager Secretary
 Staff can be Branch Manager or Secretary or Sales
Personnel

10. OVERLAPPING OPTIONAL(AND)
• Does not have to belong to member of subclass.
STAFF
Sales
PersonnelBranch Manager Secretary
 Staff can be Branch Manager or Secretary or Sales
Personnel