I've played with this one a good bit, and I have to ask someone smarter...
I have a continuous form for entering products associated with a contract, including the accounting data. The accounting data can either be a capital project or an operational expense account (subaccount). It cannot be both.
On the continuous form, I two combo boxes, one for each type of expense with rowsource of all the approved projects or subaccounts, respectively. Because it is a continuous form, I can't use an unbound box to collect the data then record it to the table AfterUpdate, because it would change all the other forms in the display. Likewise, I can't turn the boxes Visible property on or off either. I need to require the user to select EITHER a capital project or operational expense account. Since I can't really prevent it on the input side (continuous form can't prevent input on one row while allowing it on another), I instead need to institute some level of error checking that prevents the user from moving forward (BeforeUpdate?) if they have selected BOTH a capital project AND an operational expense subaccount.
Notionally, I would check both controls. If both are not null, then I would stop the update and force the user to null one of them. No idea how to do that at a technical level.
Appreciate whatever help you can offer!
Thanks,
Phil