A general query to find the difference in time (seconds) between 2 dates is
Code:
SELECT SR_Data.SR_Number, SR_Data.Open_Date, SR_Data.Closed_Date, DateDiff("s",[Open_Date],[Closed_date]) AS ET_seconds
FROM SR_Data
WHERE (((SR_Data.Closed_Date) Is Not Null));
You do not have a Holidays table. You will need one if you plan to account for Holidays.
With ms Access Saturday is Weekday 7 and Sunday is Weekday 1, so if these are your weekend days you would have to ensure(account for) records where the date represents a weekend day.
Good luck