Seems to me that you would have to generate a table with a list of all working days for a given period. Take out holidays. Then run an unmatched query between the two tables. I expect that you would use DateAdd in a loop adding + 1 to a specific starting date, check to see if it is a workday (Mon - Fri?) and not a holiday (in a table of holidays?) and, if so, append it to the Workdays table.
