Participation Constraints in ER diagram

1. PARTICIPATION
CONSTRAINTS
IN ER DIAGRAM
DBMS
In Hindi

2. Partial vs Total Participation
(MIN,MAX) Notation

3. Participation / Minimum Cardinality
An entity set may participate in a relation either totally or partially.
Partial Participation
E1 E2
Cardinality
(E1) =Many
Cardinality
(E2) = 1
Minimum
Cardinality
(E1) = 1
Minimum
Cardinality
(E1) = 0
Total Participation

4. Partial vs Total Participation
 Total participation: Each entity is involved in the relationship. i.e each entity in
the entity set must compulsorily participate in at least one relationship instance in
that relationship set. Total participation is represented by double lines.
 Partial participation: Not all entities are involved in the relationship. i.e each
entity in the entity set may or may not participate in the relationship instance in
that relationship set. Partial participation is represented by single lines.
Entity Entity
Relationship
Total participation
(mandatory)
Partial participation
(optional)

5. Example
 Double line between the entity set “Student” and relationship set “Enrolled in”
signifies total participation.
 It specifies that each student must be enrolled in at least one course.
 Single line between the entity set “Course” and relationship set “Enrolled in”
signifies partial participation.
 It specifies that there might exist some courses for which no enrollments are made.
Student Course
Enrolled in

6. Min, Max Notation
 This is a pair of numbers(m, n) that appear on the connecting line between the
entities and their relationships. The minimum number of times an entity can
appear in a relation is represented by m whereas, the maximum time it is
available is denoted by n.
 If m is 0 it signifies that the entity is participating in the relation partially,
whereas, if m is either greater than or equal to 1, it denotes total participation of
the entity.
(1 , 3) (0 , 25)
Student Course
Enrolled in
Each student can enroll minimum 1 and maximum 3 courses, and each
course can have maximum 25 students.

7. Example
In (min , max) notation based on the participation we represent min value and based
on cardinality we represent the max value.
Employee Department
Works-
In
(1 , 1) (0 , N)
Every employee works for a department and a department can have many
employees. New dept. need not have any employee.
Employee Department

8. Min, Max Notation In Different Types
Of Relationship
One-to-one
E1 E 2
R
(1 , 1) (0 , 1)
One-to-many
E1 E2
R
E1 E 2
R
(1 , N) (0 , 1)

9. Min, Max Notation In Different Types
Of Relationship
Many-to-one
Many-to-many
E1 E 2
R
(1 , 1) (0 , N)
E1 E 2
R
(1 , N) (0 , N)

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