Question

If a left outer join is performed and the tuple on the left hand side does not match with the tuple on the right hand side, what happens to the values that are preserved on the left hand side?

(a) They are given null values

(b) They are given a random value

(c) The user is asked to enter data

(d) The query is declared invalid by the compiler

This question was posed to me in an international level competition.

Enquiry is from Join Expressions in chapter Intermediate and Advanced Sql of RDBMS

Answer 1

The correct option is (a) They are given null values

For explanation I would say: If a left outer join is performed and the tuple on the left hand side does not match with the tuple on the right hand side, the remaining values are given a null value.