Quiz for Aggregate Functions

Q1: Which of the following is an aggregate function in SQL?

A. LOWER() B. SUM() C. REPLACE() D. CONCAT()

Q2: Which SQL function returns the number of rows?

A. COUNT() B. SUM() C. AVG() D. MAX()

Q3: Which aggregate function gives the total of a numeric column?

A. AVG() B. COUNT() C. SUM() D. MIN()

Q4: Which function calculates the average value of a numeric column?

A. MIN() B. MAX() C. COUNT() D. AVG()

Q5: Which function returns the smallest value in a column?

A. MIN() B. MAX() C. COUNT() D. SUM()

Q6: Which of the following functions can be used with GROUP BY?

A. SUM() B. AVG() C. COUNT() D. All of the above

Q7: What will COUNT(*) return?

A. Sum of all numeric fields B. Average of values C. Total number of rows D. Maximum value

Q8: Which clause is necessary for aggregate functions to group rows?

A. WHERE B. ORDER BY C. HAVING D. GROUP BY

Q9: What is the purpose of the HAVING clause?

A. Filter rows before grouping B. Filter groups after aggregation C. Order result D. Limit result

Q10: Which function counts only non-null values?

A. COUNT(*) B. COUNT(column) C. COUNT(ALL) D. All of them

Q11: Which function ignores NULL values by default?

A. SUM() B. AVG() C. COUNT(column) D. All of the above

Q12: Which function is used to find the total number of unique values?

A. COUNT() B. COUNT(DISTINCT) C. SUM() D. MAX()

Q13: Which aggregate function can accept DISTINCT keyword?

A. SUM() B. COUNT() C. AVG() D. All of the above

Q14: Can we use WHERE clause with aggregate functions?

A. Yes B. No C. Only in PostgreSQL D. Only with COUNT()

Q15: Which function returns a single result per group in GROUP BY?

A. COUNT() B. SUM() C. AVG() D. All of the above

Q16: Which function helps calculate average salary?

A. AVG(salary) B. SUM(salary) C. COUNT(salary) D. MAX(salary)

Q17: Which clause restricts rows before aggregation?

A. HAVING B. GROUP BY C. WHERE D. SELECT

Q18: Which function gives the total number of employees?

A. COUNT(*) B. AVG(emp_id) C. SUM(emp_id) D. MAX(emp_id)

Q19: What does COUNT(DISTINCT department_id) return?

A. Total departments B. Unique departments C. Total rows D. None

Q20: Which aggregate function returns the sum of a column values?

A. MAX() B. MIN() C. SUM() D. COUNT()