Thanks very much for the replies. You've helped me see things a little clearer.

The whole point of implementing the trigger was to update the 'Total Machine Hours' field on the MachineDetails table - but that information is entered as part of the daily timesheet info on the DailyOperatingData table so I shouldn't be storing it in two places, I just need a query (view) to show me the maximum value per machine.

It's not so much of a summary though. Well perhaps a running total. The machine operatives have to record what they see on the hour meter of machines at the start and end of their shift so the last value has to be recorded. It wouldn't be enough of a check for them to just note down the difference between start and finish values and would rely on their memory etc...

Wendell, you mentioned about adp not being supported by MS going forward, is the format they are supporting a normal access front end with linked tables?

The reason I looking down the replication route is that the remote sites may not have contant web connectivity... It is possible (since I've realised I don't need triggers and can get rid of the vba subs that update the value on the other table) that I could have a back up plan for the remote site to export data to a txt file that could be imported into sql when connectivity is restored.

I'm trying to keep things simple but it's a complex application. I think the original developer thought about normalisation and decided it was just a passing fad that wouldn't catch on.

Pete