MySQL - convert date to weekday number

In this article, we would like to show you how to convert date to weekday number in MySQL.

Quick solution:

SELECT DAYOFWEEK(date_expression) AS 'dayofweek';

or 

SELECT WEEKDAY(date_expression) AS 'weekday';

Note:

Go to this article to read about differences between DAYOFWEEK() and WEEKDAY() functions.

Simple example

In this example, we will convert example date ( 2021-01-01 11:41:31 - Friday) to weekday number.

DAYOFWEEK() example

Query:

SELECT DAYOFWEEK('2021-01-01 11:41:31') AS 'dayofweek';

Result:

WEEKDAY() example

Query:

SELECT WEEKDAY('2021-01-01 11:41:31') AS 'weekday';

Result:

Practical example

To show how to convert date to weekday number, we will use the following table:

Note:

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

Example 1 - DAYOFWEEK() function

In this example, we will convert registration_time column from users table to the day week number using DAYOFWEEK() function.

Query:

SELECT
    `id`, `username`, `registration_time`, 
    DAYOFWEEK(`registration_time`) AS 'dayofweek'
FROM `users`;

Result:

Example 2 - WEEKDAY() function

In this example, we will convert registration_time column from users table to the day week number using WEEKDAY() function.

Query:

SELECT
    `id`, `username`, `registration_time`, 
    WEEKDAY(`registration_time`) AS 'weekday'
FROM `users`;

Result:

Database preparation

create_tables.sql file:

CREATE TABLE `users` (
	`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
	`username` VARCHAR(50) NOT NULL,
	`registration_time` DATETIME NOT NULL,
	PRIMARY KEY (`id`)
);

insert_data.sql file:

INSERT INTO `users`
	(`username`, `registration_time`)
VALUES
	('Tom', '2021-01-01 11:41:31'),
	('Chris','2021-01-02 11:42:45'),
	('Jack','2021-01-03 15:13:39'),
    ('Kim','2021-01-03 15:24:51'),
    ('Marco','2021-01-04 22:35:38'),
	('Kate','2021-01-04 22:46:51'),
	('Nam','2021-01-04 22:57:37');

References

• MySQL - WEEKDAY() and DAYOFWEEK() differences