SQL Single Row Subqueries MCQ Scalar Subqueries Practice Questions

Direction: Choose the correct option

What is a single-row subquery?

A. Returns one database

B. Returns one column

C. Returns exactly one row

D. Returns one table

Direction: Choose the correct option

SELECT * FROM employees WHERE salary = (SELECT MAX(salary) FROM employees);

What does this find?

A. Lowest salary employee

B. Employee with highest salary

C. Employees with average salary

D. All employees

Direction: Choose the correct option

SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);

What does this find?

A. Lowest salary

B. Second highest salary

C. Highest salary

D. Average salary

Direction: Choose the correct option

What happens if single-row subquery returns multiple rows?

A. Error occurs

B. All rows used

C. Last row used

D. First row used

Direction: Choose the correct option

SELECT department, AVG(salary) FROM employees GROUP BY department HAVING AVG(salary) > (SELECT AVG(salary) FROM employees);

What does this query do?

A. Department list

B. Departments with above-average salary

C. Average of all

D. All departments

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