Question

What does the natural join operation do?

(a) It considers only those pairs of tuples that have the same value on those attributes that appear in the schemas of both relations

(b) It considers only those pairs of tuples that have the same value on at least one of the attributes that appear in the schemas of both the relations

(c) It considers only those pairs of tuples that do not have the same value on those attributes that appear in the schemas of both relations

(d) None of the mentioned

This question was posed to me in an online quiz.

This intriguing question originated from Basic Operations topic in chapter Introduction to Relational Model and Sql of RDBMS

Answer 1

Right option is (a) It considers only those pairs of tuples that have the same value on those attributes that appear in the schemas of both relations

To elaborate: The natural join operation considers only those pairs of tuples that have the same value on those attributes that appear in the schemas of both the relations. The natural join operation operates on 2 relations and gives a relation as the result.