ER Model Basics (Contd.)
Relationship: Association among two or more entities. E.g., Ed works in Pharmacy department.
Relationship Set: Collection of similar relationships.
- An n-ary relationship set R relates n entity sets E1 ... En; each relationship in R involves entities e1 ? E1, ..., en ? En
- Same entity set could participate in different relationship sets, or in different “roles” in same set.