How to count date difference excluding weekend and holidays in MySQL

Question

I need to count days (business days) between two dates excluding weekend (most important) and holidays

SELECT DATEDIFF(end_date, start_date) from accounts
         


        

Answer 1

Create a table that contains all the weekends and holidays for the next 100whatever years.

You need to be able to specify when a day is a 'holiday' given that no one knows what the holidays will be for 2052 yet, you will not be able to make an accurate function at this time anyway. just update your non-work day table each year when the holidays become known (but you will always know the weekends).

Then your query becomes:

SELECT DATEFIFF(end_date, start_date) - COALESCE((SELECT COUNT(1) FROM nonWorkDays WHERE nonWorkDays.date BETWEEN start_date AND end_date), 0)
FROM accounts

If you really need to write a DATEDIFFWITHOUTWEEKENDSORHOLIDAYS function then just use the above and create a function (there's plenty of resources on how to make functions in each RDBMS).. just be sure to give it a better name. ^_^

One thing you will need to fix is I think there's a +1 missing somewhere in the above, for example DATEDIFF(today, today) if today is a weekend will return -1 instead of returning 0.