Question

For a binary many to many relationship, 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

The question was posed to me in quiz.

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

Answer 1

Correct option is (c) Union of primary keys

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