This set of RDBMS Multiple Choice Questions & Answers (MCQs) focuses on “Join Expressions”.
1. The on condition appears at the _______ of the join expression
a) Beginning
b) End
c) Between
d) The on condition is not related to join expression
View Answer
Explanation: The on condition appears at the end of the join expression. Because it states the condition that the relations under the join operations get matched based on.
2. What is the difference between a join and an outer join operation?
a) There is no difference
b) Join preserves a few tuples that are otherwise lost in the outer join
c) Outer join preserves a few tuples that are otherwise lost in the join
d) An outer join can be used only on outer queries whereas a join operation can be used in Subqueries
View Answer
Explanation: The outer join operation preserves a few tuples that are otherwise lost in the join operation. The outer join operation preserves the tuples to the right of the operation.
3. The join operations that do not retain mismatched tuples are called as _________ operations
a) outer join
b) natural join
c) full outer join
d) inner join
View Answer
Explanation: The join operations that do not retain mismatched tuples are called as inner join operations. The inner join operations do not preserve any tuples that are otherwise preserved in the outer join operation.
4. What is the function of a left 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
View Answer
Explanation: The left outer join operation preserves the tuples named before the operation.
5. 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
View Answer
Explanation: 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.
6. What is the function of a right 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
View Answer
Explanation: The right outer join operation preserves the tuples named after the operation.
7. What is the function of inner 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
View Answer
Explanation: The join operations that do not retain mismatched tuples are called as inner join operations. The inner join operation does not preserve any tuples on either side of the relation.
8. State true or false: on and where behave differently for outer join
a) True
b) False
View Answer
Explanation: The on condition is a part of the outer join syntax but the where clause isn’t.
9. Which off the following is not a valid type of join?
a) left outer join
b) outer join
c) join
d) full join
View Answer
Explanation: There is no such join called as full join. There is a full outer join but a full join does not exist.
10. 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
View Answer
Explanation: 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.
Sanfoundry Global Education & Learning Series – RDBMS.
To practice all areas of RDBMS, here is complete set of 1000+ Multiple Choice Questions and Answers.
If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]
- Check RDBMS Books
- Check Computer Science Books
- Practice Computer Science MCQs
- Apply for Computer Science Internship
