MySQL day of week ending on Friday

: Joel Lipman; MySQL; 26 April 2012; Hits: 10058

What?
Week Ending Date has been requested a lot more frequently now. It's an odd one but the example below shows how to do this for when the week ends on Friday. Assuming it starts on the previous Saturday.

Why?
Problems with MySQL weeks always starting on Sunday means this isn't very useful. I have another system which starts on Monday and ends on the following Sunday. The solution below is for the opposite, where the week starts on the previous Saturday and ends on the last working day of the week.

The Solution
Where "givenDate" is the given date you have to calculate the last working day of:

copy raw

-- SAMPLE DATES ARE: --
-- 2012-04-27 10:00:00 -- is a Friday
-- 2012-04-28 11:00:00 -- is a Saturday
-- 2012-04-29 12:00:00 -- is a Sunday


DATE_ADD(
	givenDate, 
	INTERVAL (
		6 - DATE_FORMAT(
			DATE_ADD(givenDate, INTERVAL 1 DAY), \'%w\'
		)
	) DAY
) AS WeDate


-- OR --

DATE_ADD(
	givenDate, 
	INTERVAL (
		7 - DAYOFWEEK(
			DATE_ADD(givenDate, INTERVAL 1 DAY)
		)
	) DAY
) AS WeDate


-- yields
-- 2012-04-27  -- this Friday
-- 2012-05-04  -- next Friday
-- 2012-05-04  -- next Friday

-- SAMPLE DATES ARE: --
-- 2012-04-27 10:00:00 -- is a Friday
-- 2012-04-28 11:00:00 -- is a Saturday
-- 2012-04-29 12:00:00 -- is a Sunday
DATE_ADD(
givenDate,
INTERVAL (
6 - DATE_FORMAT(
DATE_ADD(givenDate, INTERVAL 1 DAY), \'%w\'
)
) DAY
) AS WeDate
-- OR --
DATE_ADD(
givenDate,
INTERVAL (
7 - DAYOFWEEK(
DATE_ADD(givenDate, INTERVAL 1 DAY)
)
) DAY
) AS WeDate
-- yields
-- 2012-04-27 -- this Friday
-- 2012-05-04 -- next Friday
-- 2012-05-04 -- next Friday

Not sure why this works, thinking about it hurts my head but it worked with my test data (selecting current week days then the following saturday and sunday -- both saturday and sunday returned week ending date as next week).

If you were starting on Monday
...So if your week ends on a Sunday

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-- SAMPLE DATES ARE: --
-- 2012-04-27 10:00:00 -- is a Friday
-- 2012-04-28 11:00:00 -- is a Saturday
-- 2012-04-29 12:00:00 -- is a Sunday


DATE_ADD(
	givenDate, 
	INTERVAL (
		6 - weekday(givenDate)
	) DAY
) AS WeDate


-- yields
-- 2012-04-29  -- this Sunday
-- 2012-04-29  -- this Sunday
-- 2012-04-29  -- this Sunday