SQL Subqueries and Functions Quiz

Which of the following best describes a correlated subquery?

• It runs only once and returns a single value.

• It is independent of the outer query.

• It references columns from the outer query.

• It cannot be used in WHERE clauses.

Which SQL clause can a subquery not be used in?

• SELECT

• GROUP BY

• WHERE

• FROM

What is the main advantage of using a CTE over a subquery?

• CTEs are faster.

• CTEs allow recursive operations and improve readability.

• CTEs are always written inside the FROM clause.

• CTEs return multiple result sets.

In SQL, what does the OVER() clause do in a window function?

• It joins multiple tables.

• It groups rows into a temporary table.

• It defines the window of rows for the function to operate on.

• It filters results before aggregation.

Which of the following functions is typically used with window functions?

• SUM()

• COUNT()

• ROW_NUMBER()

• MAX()

A subquery can return multiple rows and columns.

Window functions always require a GROUP BY clause.

Recursive CTEs must contain at least two SELECT statements: one anchor and one recursive member.

The EXISTS keyword returns true if the subquery returns one or more rows.

Window functions and aggregate functions serve exactly the same purpose.