Free Test Aggregate Functions an... – Databas...

Q1: Which SQL function returns the total number of rows?

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

Q2: Which aggregate function calculates the average value?

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

Q3: Which function returns the largest value in a column?

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

Q4: Which aggregate function returns the smallest value?

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

Q5: Which function returns the sum of all values in a numeric column?

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

Q6: What does GROUP BY do in an SQL query?

A. Groups rows that have the same values in specified columns B. Sorts the rows C. Filters rows D. Joins tables

Q7: Which clause filters grouped records based on aggregate conditions?

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

Q8: Can aggregate functions be used without GROUP BY?

A. Yes, they operate on entire result set B. No, always need GROUP BY C. Only COUNT can be used D. Only SUM can be used

Q9: Which aggregate function can count only distinct values?

A. COUNT(DISTINCT column_name) B. COUNT(column_name) C. SUM(DISTINCT column_name) D. AVG(DISTINCT column_name)

Q10: What happens if you use aggregate functions on columns with NULL values?

A. NULL values are ignored B. NULL values cause error C. NULL values counted as zero D. NULL values cause query to fail

Q11: Which function counts all rows including NULLs?

A. COUNT(*) B. COUNT(column_name) C. SUM() D. AVG()

Q12: Which clause cannot be used with aggregate functions?

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

Q13: What will this query return? SELECT department, COUNT(*) FROM employees GROUP BY department;

A. Number of employees in each department B. Total number of employees C. Departments with no employees D. All employee details

Q14: Which aggregate function can be used to calculate total salary?

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

Q15: How do you filter groups having more than 5 employees?

A. HAVING COUNT(*) > 5 B. WHERE COUNT(*) > 5 C. GROUP BY COUNT(*) > 5 D. ORDER BY COUNT(*) > 5

Q16: Which of these is NOT an aggregate function?

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

Q17: What does this SQL do? SELECT MAX(salary) FROM employees;

A. Returns highest salary B. Returns average salary C. Returns total salary D. Returns minimum salary

Q18: Which function returns the median?

A. No direct SQL aggregate function B. MEDIAN() C. AVG() D. SUM()

Q19: Which aggregate function works with dates?

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

Q20: Can GROUP BY be used with multiple columns?

A. Yes B. No C. Only with one column D. Only with aggregates

Quiz for Aggregate Functions and Grouping