Preventing Changes To A Field Containing Information

[jaythom]

Hello,

I am curious how to prevent changes to a field after that field has had data entered into it.

I tried:

Before Update

If IsNull(Me!User) Then
MsgBox "This is allowed"
Else
MsgBox "This is not allowed"
Cancel = True
End If

I figured that until the User field had the value saved to the field, it would have a Null value. I checked in the Immediate window and debug.print showed this to be true. With the code above, it would not prevent changes even after the field previously contained information.

Any help would be greatly appreciated!

John

 

[Rich]

http://www.access-programmers.co.uk/forums/showthread.php?s=&postid=206697#post206697

 

[WayneRyan]

John,

If IsNull(Me.User.OldValue) Then
   MsgBox ("This is allowed")
Else
   MsgBox ("This NOT is allowed")  
   Me.User = Me.User.OldValue
End If

Wayne