Issues settingup a form to subtract from records

[funkenstein]

I am developing a database for a local team's fan club which has three tables- tblMatches, tblEvents and tblBookings, each of which has a corresponding form to add a record to the database. The primary key for tblMatches is 'Match ID' and the primary key for tblEvents is 'Event ID'. Both also have a field called 'Seats remaining', or the number of seats left that can be booked. Seats are booked through the form for tblBookings which has four fields: Event ID, Seatnumberevent, Match ID and Seatnumbermatch and a button called 'Add Booking'. How can the 'Add Booking' button be set up so that when it is clicked, it adds a record to tblBooking and also subtracts 1 from 'Seats remaining' for the corresponding event or match? Thanks.

[June7]

Review http://www.dreamincode.net/forums/to...ventory-table/

As stated in that thread, saving aggregate data is problemmatic. Here is link to a database that demonstrates how to save booking records and track the balance of 'seats remaining' https://www.box.com/shared/c23kknkyyq