Relationships and Relationship sets of database management system free pdf
A relationship is an association among two or more entities. For example we may have the relationship that Antony works in the Marketing department. A relationship type R among the n entity types E1,E2, ,En defines a set of associations or a relationship set- among entities from these entity types. Informally each relationship instance ri in R is an association of entities, where the association includes exactly one entity from each participating entity type.