Control Data in Form

[vip2442]

Hi i want to know how can i control CheckBox
Ex:

*- If i have record for and the primiry key is the ID

*- When i type the ID i get the an other data for that record

*- If i change address in that form and the checkBox is True i want to stop update that record and get messege for that.

OR

Checking all address in that Form if it equals to the new address entry Then get Messege.

Why I need it?
I have FORM to Borrowing Books and i don't want any one to Borrow Book two times.

 

[Sergeant]

This was confusing enough yesterday, when it was called Control the CheckBox in form.