MS SQL Server - 23 - Union and Case MCQ

23 – Union and Case MCQ

1 / 20

1. What is the purpose of the UNION operator in SQL Server?

Combine the result sets of two or more SELECT queries

Join two tables based on a common column

Subtract the result sets of two SELECT queries

Intersect the result sets of two SELECT queries

2 / 20

2. Which set operator in SQL Server returns all distinct rows from the result set of the first query and all distinct rows from the result set of the second query?

UNION

EXCEPT

UNION ALL

INTERSECT

3 / 20

3. What does the INTERSECT operator in SQL Server do?

Returns all rows from either result set, including duplicates

Returns all rows from the first result set that are not in the second result set

Returns all rows from the second result set that are not in the first result set

Returns all distinct rows present in both result sets

4 / 20

4. When using the UNION operator in SQL Server, does it include duplicate rows in the result set?

No, it removes duplicates

Yes, it includes duplicates

It throws an error if duplicates are present

It depends on the database settings

5 / 20

5. Which SQL Server set operator is used to return all rows from the first result set that are not present in the second result set?

INTERSECT

UNION ALL

EXCEPT

UNION

6 / 20

6. What is the purpose of the CASE expression in SQL Server?

To join two tables

To perform arithmetic operations

To conditionally return values based on specified conditions

To create a new table

7 / 20

7. How do you define a simple CASE expression in SQL Server?

Using the WHEN keyword followed by a condition

Using the IF-ELSE statement

Using the SELECT keyword followed by a value

Using the CREATE CASE statement

8 / 20

8. In a CASE expression, what value is returned if none of the specified conditions is true?

An error is thrown

NULL

An empty string

9 / 20

9. Which SQL Server CASE expression is used to compare a single expression with multiple values?

Nested CASE expression

Simple CASE expression

Searched CASE expression

Complex CASE expression

10 / 20

10. What is the primary advantage of using CASE expressions in SQL Server?

They simplify table creation

They improve query performance

They allow for conditional result customization

They reduce the need for joins

11 / 20

11. Which SQL Server set operator returns all rows from both result sets, including duplicates?

UNION

UNION ALL

INTERSECT

EXCEPT

12 / 20

12. What is the purpose of the EXCEPT operator in SQL Server?

Returns all distinct rows present in both result sets

Returns all rows from the second result set that are not in the first result set

Combines the result sets of two SELECT queries

Performs a Cartesian product of two tables

13 / 20

13. When using the INTERSECT operator in SQL Server, is the order of columns important between the two result sets?

INTERSECT does not require column alignment

Yes, the order must be identical

It depends on the database settings

No, the order does not matter

14 / 20

14. In a CASE expression, what keyword is used to specify the value to return when a condition is true?

END

THEN

SELECT

ELSE

15 / 20

15. How do you create a searched CASE expression in SQL Server?

Using the IF-ELSE statement

Using the SELECT keyword followed by a value

Using the WHEN keyword followed by a condition

Using the CREATE CASE statement

16 / 20

16. In a searched CASE expression, can you specify multiple conditions for a single result?

Yes, using the OR operator

Yes, using the AND operator

No, only one condition per result is allowed

Only if the conditions are enclosed in parentheses

17 / 20

17. What value is returned by a CASE expression if none of the specified conditions is true, and there is no ELSE clause?

An empty string

NULL

An error is thrown

18 / 20

18. What is the primary purpose of the COALESCE function in SQL Server?

To return the first non-null expression in a list

To perform string concatenation

To perform bitwise operations

To create a new table

19 / 20

19. Which SQL Server function is used to handle NULL values within expressions?

IGNORENULL

NVL

ZEROIFNULL

ISNULL

20 / 20

20. In a CASE expression, can you use a subquery as a condition?

Yes, in both simple and searched CASE expressions

Yes, but only in a simple CASE expression

Only if the subquery returns a single value

No, subqueries are not allowed in CASE expressions

Your score is

MS SQL Server – 23 – Union and Case MCQ