Aggregate Functions In MySQL

Question 1

What are aggregate functions in MySQL used for?

Answer 1

To perform calculations on a set of values and return a single value as a result

Question 2

What does the COUNT() function do?

Answer 2

Counts the number of rows that meet a specified condition

Question 3

What is the syntax for the COUNT() function?

Answer 3

COUNT(column_name) or COUNT(*)

Question 4

Provide an example of using COUNT() in SQL.

Answer 4

SELECT COUNT(*) FROM customers

Question 5

What does the SUM() function calculate?

Answer 5

The sum of values in a specified column

Question 6

What is the syntax for the SUM() function?

Answer 6

SUM(column_name)

Question 7

Provide an example of using SUM() in SQL.

Answer 7

SELECT SUM(amount) FROM orders

Question 8

What does the AVG() function calculate?

Answer 8

The average value of a specified column

Question 9

What is the syntax for the AVG() function?

Answer 9

AVG(column_name)

Question 10

Provide an example of using AVG() in SQL.

Answer 10

SELECT AVG(price) FROM products

Question 11

What does the MIN() function return?

Answer 11

The minimum value of a specified column

Question 12

What is the syntax for the MIN() function?

Answer 12

MIN(column_name)

Question 13

Provide an example of using MIN() in SQL.

Answer 13

SELECT MIN(order_date) FROM orders

Question 14

What does the MAX() function return?

Answer 14

The maximum value of a specified column

Question 15

What is the syntax for the MAX() function?

Answer 15

MAX(column_name)

Question 16

Provide an example of using MAX() in SQL.

Answer 16

SELECT MAX(salary) FROM employees

Question 17

What is the purpose of the GROUP BY clause?

Answer 17

To group the results based on one or more columns

Question 18

What is the syntax for using aggregate functions with GROUP BY?

Answer 18

SELECT column_name, aggregate_function(column_name) FROM table_name GROUP BY column_name

Question 19

Provide an example of using GROUP BY with COUNT() in SQL.

Answer 19

SELECT country, COUNT(*) FROM customers GROUP BY country

Question 20

Do aggregate functions ignore NULL values?

Answer 20

Yes, except for COUNT(*)

Question 21

What keyword can be used within COUNT() to count distinct values?

Answer 21

DISTINCT

Question 22

What are some additional aggregate functions mentioned?

Answer 22

• GROUP_CONCAT()
• STDDEV()
• VARIANCE()

Question 23

Fill in the blank: Aggregate functions are often used in combination with other clauses like _______ and _______ to filter results.

Answer 23

[WHERE, HAVING]