In my Access bookings system you select a number of Units and a start and end booking time. I need to calculate the cost of each Unit for the booking as well as a total cost for all Units in the booking.
The information is stored in two tables: a bookings table called tblHourPeriod with the resources used and fromTime and thruTime fields. A second table called tblUnit has the list of resources and their rate card costs (per hour). I need the query to calculate the difference between fromTime and thruTime and then multiply this by the rate card. Any ideas how to do this?