SQL Screening Test

By Collab Team Contributor / February 15, 2025

SQL Screening Test

1 / 20

What is the maximum number of clustered indexes allowed per table in SQL Server?

Unlimited

2 / 20

What is the function of the DISTINCT keyword in SQL?

Groups rows based on unique values

Joins two tables on unique values

Deletes duplicate rows permanently

Filters out duplicate rows in query results

3 / 20

In SQL Server, which function is used to get the current system date and time?

NOW()

SYSDATE()

CURRENT_TIMESTAMP

GETDATE()

4 / 20

Which SQL statement is used to remove all rows from a table without logging individual row deletions?

DROP

DELETE

TRUNCATE

REMOVE

5 / 20

What will happen if you try to insert a duplicate value in a column with a UNIQUE constraint?

It will return an error

It will ignore the duplicate and insert

It will insert successfully

It will replace the existing value

6 / 20

What happens when a NULL value is compared using the = operator?

It throws an error

It returns FALSE

It returns TRUE

It returns NULL

7 / 20

What is the default isolation level in SQL Server?

READ UNCOMMITTED

READ COMMITTED

REPEATABLE READ

SERIALIZABLE

8 / 20

Which SQL clause is used to filter grouped records?

GROUP BY

HAVING

ORDER BY

WHERE

9 / 20

Which command is used to modify an existing table structure?

ALTER

CHANGE

MODIFY

UPDATE

10 / 20

What does the UNION operator do in SQL?

Combines results of multiple SELECT queries without duplicates

Merges two tables permanently

Joins two tables on a common key

Combines results of multiple SELECT queries with duplicates

11 / 20

What will happen if a subquery returns multiple rows in a scalar subquery context?

It will return only the first row

It will return all row

It will return NULL

It will cause an error

12 / 20

What will be the result of a CROSS JOIN between two tables with 5 and 10 rows respectively?

5 rows

15 rows

50 rows

10 rows

13 / 20

Which type of join includes all records from the left table and only matching records from the right table?

RIGHT JOIN

LEFT JOIN

FULL JOIN

INNER JOIN

14 / 20

What does the SQL CASE statement do?

Defines conditional logic inside a query

Creates a new table

Checks foreign key constraints

Handles NULL values

15 / 20

What is the primary function of an index in SQL?

To improve query performance

To store duplicate records

To enforce referential integrity

To define foreign key relationships

16 / 20

In SQL, what is the purpose of the RANK() function?

Assigns a unique rank to each row with possible gaps

Returns the number of rows in a table

Computes the sum of a column

Assigns a unique rank to each row without gaps

17 / 20

In SQL, what does the COALESCE function do?

Replaces NULL values with a default value

Returns the first non-null value in a list

Returns the last non-null value in a list

Joins multiple tables

18 / 20

Which SQL function is used to remove leading and trailing spaces from a string?

RTRIM()

TRIM()

LTRIM()

REPLACE()

19 / 20

Which SQL statement is used to check for the existence of rows in a subquery?

JOIN

HAVING

EXISTS

20 / 20

What does the ROW_NUMBER() function do in SQL?

Groups rows based on a column

Sorts rows in descending order

Assigns a unique sequential number to rows