MySQL - average value for grouped rows

In this article, we would like to show you how to find avg value for grouped rows in MySQL.

Quick solution:

SELECT `column1`, AVG(`column2`)
FROM `table_name`
GROUP BY `column1`;

Practical example

To show how to find avg value for grouped rows, we will use the following table:

Note:

At the end of this article you can find database preparation SQL queries.

Example

In this example, we will select the average salary value for each department.

Query:

SELECT department_id, AVG(salary) AS 'avg_salary'
FROM `users`
GROUP BY `department_id`;

Result:

Database preparation

create_tables.sql file:

CREATE TABLE `users` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(50) NOT NULL,
	`surname` VARCHAR(50) NOT NULL,
	`email` VARCHAR(100),
	`department_id` INT(10) UNSIGNED,
    `salary` DECIMAL(15,2) NOT NULL,
	PRIMARY KEY (`id`)
);

insert_data.sql file:

INSERT INTO `users`
	( `name`, `surname`, `email`, `department_id`, `salary`)
VALUES
	('John', 'Stewart', 'john@email.com', 1, '3512.00'),
	('Chris', 'Brown', 'chris@email.com', 2, '1344.00'),
	('Kate', 'Lewis', NULL, 3, '6574.00'),
	('Ailisa', 'Gomez', 'ailisa@email.com', 3, '6500.00'),
	('Gwendolyn', 'James', NULL, 2, '4200.00'),
	('Simon', 'Collins', NULL, 1, '3320.00'),
	('Taylor', 'Martin', NULL, 2, '1500.00'),
	('Andrew', 'Thompson', 'andrew@email.com', 1, '2100.00');