# Domo Idea Exchange - Beast Modes - Business Days Prior to Today

Greetings! This is another post highlighting a beast mode from my Domo IDEAs conference session. This one covers how to calculate the number of business days between two dates.

Problem:

How to calculate the number of business days (Monday - Friday) between two dates.

Solution:

We need to calculate the number of days in between the two dates, remove the days which are weekends and an extra day if it's not a Saturday. The logic works because we don't want to count today so we subtract the extra day but because Saturday comes before a Sunday we still need to remove that single day.

Let's break it down into the different steps.

First, get the number of days between the two dates:

```-- Author:
-- Created:
-- Description:
-- Calculate the number of actual days between the two dates
DATEDIFF(CURRENT_DATE(), `dt`)

```

Next determine the number whole weeks and multiply that number by 2 to subtract from the date difference. We determine the number of whole weeks between the two by calculating the first day of the week for each (This is the same as subtracting the difference of 7 and the day of week for the date)

```-- Author:
-- Created:
-- Description:
-- Days of weekends between the two dates
DATEDIFF(CURRENT_DATE() + INTERVAL (1 - DAYOFWEEK(CURRENT_DATE())) DAY, `dt` + INTERVAL (1 - DAYOFWEEK(`dt`)) DAY) / 7 * 2
```

Finally we have a condition to check if the start date is a Saturday or not. This is to remove the current date with Saturday being the exception since it precedes Sunday and is a partial week.

```-- Author:
-- Created:
-- Description:
-- If we don't start on a Saturday remove the current day so we don't count it
CASE WHEN DAYOFWEEK(`dt`) <> 7 THEN 1 ELSE 0 END

```

Finally tying it all together:

```-- Author:
-- Created:
-- Description:
-- Calculate the number of actual days between the two dates
DATEDIFF(CURRENT_DATE(), `dt`)
-- Calculate the number of whole weeks:
-- Calculate the number of days between the start of the week for both dates
- DATEDIFF(
-- Get the last of the prior week for our current date
CURRENT_DATE() + INTERVAL (1 - DAYOFWEEK(CURRENT_DATE())) DAY,
-- Get the last day of the prior week for our start date
`dt` + INTERVAL (1 - DAYOFWEEK(`dt`)) DAY
) / 7 * 2 -- Divide by 7 to get the number of whole weeks and multiply it by 2 to get the number of weekend days (Saturday and Sunday)

-- If we don't start on a Saturday remove the current day so we don't count today
- (CASE WHEN DAYOFWEEK(`dt`) <> 7 THEN 1 ELSE 0 END)
```

Notes:

This is a simplified calculation of business days. It doesn't take into account holidays or other days your business may be closed.

Also, this will return positive numbers for the past and negative numbers for dates in the future. This can be changed by simply multiplying the final business days number by -1.