Question

What is the function of a full outer join?

(a) It preserves tuples only in the relation named before the operation

(b) It preserves tuples only in the relation named after the operation

(c) It preserved tuples in the relations named on both the sides of the operation

(d) It does not preserve any tuples on either side of the relation

The question was asked in quiz.

This intriguing question originated from Join Expressions topic in portion Intermediate and Advanced Sql of RDBMS

Answer 1

Right choice is (c) It preserved tuples in the relations named on both the sides of the operation

For explanation I would say: The full outer join operation preserves the tuples named on both the sides of the operation. Unlike the inner join, outer joins preserve tuples from either or both sides of the operation.