Help! Disallow changes but allow additions to fields in tabbed form

[Ian]

I have a form with tabs to collect product testing
information. I need a way to collect additional data if
changes to existing data are being made. I can't set Allow
Updates to No because the data may be entered for all
fields in one shot or it may be input at different times
for the record. Does someone know of a way to prompt for
(exUsername/Password only if existing data on the form
is being changed. ie: prompt if PartSize was 1 and is
being changed to 2 but don't prompt if PartSize was blank
and a value is now being entered.

 

[Alphonse Giambrone]

In the beforeupdate event of the control you could check the 'oldvalue' and
if it is not null, prompt.
This would require code for each control.

It would be easier and more user friendly to put code in the oncurrent event
of the form and loop through each textbox checking to see if they contain
data and if so, lock it.
To allow edits, add a button for your prompt and then loop through the
controls again and unlock all.

HTH