Question

What is a participation role? when is it necessary to use role names in the description of relationship types?

Answer 1

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What is a participation role?
Participation role is defined as the part of relationship in whicheach entity participates in a relationship. It is necessary to use role name in the description of relationship type when the same entity type participates more than once in a relationship type in different roles. Or, we could say thatrole names are necessary in recursive relationships. Ans 2. Two alternatives for specifying structural constraints on relationship types are cardinality ratio and participation. Cardinality ratio for a binary relationship meansthe number of relationship instances that an entity can participate in.

As in real world, miniworld entities (of same or different entity type) are related to each other.

For example: An employee is related to a department in which he works in a company.

So we can say that a relationship may exist between various entities (of same or different entity type).

Each entity type that participates in a relationship type plays a particular role in the relationship.

Participation Role or Role name signifies role that a participating entity from the entity type plays in each relationship instance, and helps to explain what relationship means.

For example: In WORKS_FOR relationship type, EMPLOYE plays the role of worker and DEPARTMENT plays role of department or employer. In figure below an employee works for department. E1 and E3 work for D1 and E2 works for D2.

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Answer 2

Answer:

The answer to the given question is explained in the explanation.

Explanation:

What is a participation role?

The participation role is part of a connection in which each entity participates.

When the same entity type participates in a relationship type in many roles, the role name must be used in the description of the relationship type.

Alternatively, role names are required in recursive relationships.

Cardinality ratio and participation are two options for expressing structural limitations on relationship kinds. In a binary relationship, the cardinality ratio refers to the number of relationship instances in which an entity can participate.

Miniworld entities (of the same or distinct entity type) is related to one another, much like in the actual world.

For example:

There's a relationship between an employee and the department he works at in his company.

As a result, we can argue that various entities may have a relationship

Each entity type in a relationship serves a specific role in the relationship.

Participation Role or Role name signifies the role that a participating entity from the entity type plays in each relationship instance, and helps to explain what relationship means.

For example:

In WORKS_FOR relationship type, EMPLOYE plays the role of worker and DEPARTMENT plays role of department or employer.

In figure below an employee works for department.

E1 and E3 work for D1 and E2 works for D2.

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