Question

For a n-ary relationship set without arrows, the ________ of the participating entity sets becomes the prime attribute

(a) Intersection of primary keys

(b) Primary key of either one

(c) Union of primary keys

(d) Primary key on the many side

This question was posed to me in class test.

I'd like to ask this question from Reduction to Relational Schema in division Database Design and the ER Model of RDBMS

Answer 1

The correct option is (c) Union of primary keys

To elaborate: For a binary many to many relationship, the union of the primary keys of the participating entity sets becomes the prime attribute.