EN
MySQL - count rows with NULL values
0
points
In this article, we would like to show you how to count rows with NULL
values in MySQL.
Quick solution:
SELECT COUNT(*) AS 'alias_name'
FROM `table_name`
WHERE `column_name` IS NULL;
Practical example
To show you how to count rows with NULL
values, we will use the following users
table:
Note:
At the end of this article you can find database preparation SQL queries.
Example
In this example, we will count the number of rows with NULL
values in department_id
column.
Query
SELECT COUNT(*) AS 'NULL_values_in_column'
FROM `users`
WHERE `department_id` IS NULL;
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,
`department_id` INT(10) UNSIGNED,
`salary` DECIMAL(15,2) NOT NULL,
PRIMARY KEY (`id`)
);
insert_data.sql
file:
INSERT INTO `users`
( `name`, `surname`, `department_id`, `salary`)
VALUES
('John', 'Stewart', 1, '6000'),
('Chris', 'Brown', 2, '6000'),
('Kate', 'Lewis', 3, '4000'),
('Ailisa', 'Gomez', NULL, '4000'),
('Gwendolyn', 'James', NULL, '4000'),
('Simon', 'Collins', 4, '4000'),
('Taylor', 'Martin', 2, '2000'),
('Andrew', 'Thompson', NULL, '2000');