I'm not sure I follow. I'm just trying to calculate the difference from the two dates, excluding weekends and holidays.
So, if Due_Date is 9/19/2014 and Result_Date is 9/19/2014, then TAT is 0
if Due_Date is 9/26/2014 and Result_Date is 9/29/2014, then TAT is 1 (the weekend dates are...