Participation Constraints in DBMS
Participation constraints in DBMS
In this article we will learn about Participation constraints in DBMS.
In a Relationship,
Participation constraint specifies the presence of an entity when it is related to another entity in a relationship type. It is also called the minimum cardinality constraint.
This constraint specifies the number of instances of an entity that are participating in the relationship type.
- There are two types of Participation constraint:
- Total participation
- Partial participation
Total participation constraint
- It specifies that each entity present in the entity set must mandatorily participate in at least one relationship instance of that relationship set,for this reason, it is also called as mandatory participation
- It is represented using a double line between the entity set and relationship set
Example of total participation constraint
- It specifies that each student must be enrolled in at least one course where the “student” is the entity set and relationship “enrolled in” signifies total participation
- It means that every student must have enrolled at least in one course
- It specifies that each entity in the entity set may or may not participate in the relationship instance of the relationship set, is also called as optional participation
- It is represented using a single line between the entity set and relationship set in the ER diagram
Example of partial participation
A single line between the entities i.e courses and enrolled in a relationship signifies the partial participation,which means there might be some courses where enrollments are not made i.e enrollments are optional in that case