Participation Constraint

For Complete YouTube Video: Click Here

In this class, we will understand Participation Constraint.

We have already discussed the concept of the Cardinality Ratio.

Table of Contents

Participation is opposite to the cardinality ratio.

Participation Constraint specifies the minimum number of relationship instances that an entity can participate.

We will consider the ER-Diagram that we have obtained so far.

We will also consider the relationship instances as shown below.

From the works_for relationship instance, it states that the employee has a minimum participation of one.

We cannot conclude from the relationship instances diagram.

The constraints in the requirements state that an employee should belong to a department.

A department should have an employee.

The participants are represented by Full Participation and Partial Participation.

Full Participation: If all the entities of an entity type have at least one participation instance, then it is full participation.

Partial Participation: If some entities of an entity type do not have an instance, then it is partial participation.

The employee entity type has partial participation as some of the employees are not having relationship instances.

All the employees cannot be managers.

The department entity type has full participation as a department should have a manager.

Double lines represent the full participation, and the partial participation is single lines, as shown below.