Question

What is a participation role? State the circumstances under which the use of role names becomes necessary in description of relationship types.

Answer 1

Each entity type that participates in a relationship type plays a particular role in the relationship. The role name signifies the role that a participating entity of an entity type plays in each relationship instance. 

In PREPARED BY relationship type, EMPLOYEE plays the role of document creator and voucher plays the role of document created. Entity TEACHER and Entity STUDENT are related with a relationship TEACHER – teach – STUDENT. The teaches is a participating role in the entity set TEACHER and STUDENT