The MySQL WEEKDAY function is used to determine the day of the week for a given date. It returns an integer value representing the day of the week, where Monday is assigned the value 0 and Sunday is assigned the value 6. This function can be particularly useful in scenarios where you need to perform different actions or make decisions based on the day of the week.

Syntax

Here is the basic syntax of the WEEKDAY function:

WEEKDAY(date)

date: The date for which you want to find the day of the week.

Example

Let’s look at an example:

SELECT WEEKDAY('2024-01-01') AS DayOfWeek;

In this example, the function is applied to the date ‘2024-01-01’. Since January 1, 2024, is a Monday, the result of the query will be:

+-----------+
| DayOfWeek |
+-----------+
|    0      |
+-----------+

This indicates that Monday is the first day of the week and is represented by the value 0.

You can also use the result of the WEEKDAY function in combination with other MySQL functions or in conditional statements to perform specific actions based on the day of the week. For instance, you might want to run a certain query only on weekdays or weekends.

Here’s an example of how you might use the WEEKDAY function in a conditional statement:

SELECT
    CASE
        WHEN WEEKDAY(NOW()) BETWEEN 0 AND 4 THEN 'Weekday'
        WHEN WEEKDAY(NOW()) IN (5, 6) THEN 'Weekend'
        ELSE 'Unknown'
    END AS DayType;

In this case, the query checks the current day of the week using NOW and categorizes it as ‘Weekday’, ‘Weekend’, or ‘Unknown’ based on the result of the WEEKDAY function.

Understanding the MySQL WEEKDAY function and incorporating it into your queries allows for dynamic and flexible data processing based on the day of the week.