随着时间的推移获得SQL / Excel的日期差异

I am trying to get a date difference to determine cycle time of when something arrives to completion. However, I need the product to count towards cycle time average for all days it is here. So, something along the lines if arrivdate='8/16' but completiondate='8/24', I need for the cycle time for this product to be 1 on '8/17', 2 on '8/18', etc until it is 8 on '8/24' and then stops counting. I am willing to do it in either Excel or SQL, if there is a fast way to do it. Below is an example of the data in an Excel sheetI am trying to get a date difference to determi