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Chapter 11: Automatic Procedures and Events
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Preventing data validation from being destroyed
The procedure in this section demonstrates how to prevent users from copying
data and wiping out data validation rules. This example assumes that the
worksheet has a range named InputArea, and this input area contains data
validation rules (set up by using the Data➪Data Tools➪Data Validation command).
The range can have any validation rules you want.
A workbook that contains this code is available at this book’s Web site:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim VT As Long
‘Do all cells in the validation range
‘still have validation?
On Error Resume Next
VT = Range(“InputRange”).Validation.Type
If Err.Number 0 Then
Application.Undo
MsgBox “Your last operation was canceled.” & _
“It would have deleted data validation rules.”, _
vbCritical
End If
End Sub
The procedure is executed whenever a cell is changed. It checks the validation
type of the range (named InputRange) that is supposed to contain the
data validation rules. If the VT variable contains an error, that means that
one or more cells in the InputRange no longer have data validation (the user
probably copied some data over it). If that’s the case, the code executes the
Undo method of the Application object and reverses the user’s action. Then
it displays a message box.
The net effect? It’s impossible to wipe out the validation rules by copying
data. When Excel is broken, use VBA to fix it.
Events Not Associated with Objects
The events that I discuss previously in this chapter are associated with either
a workbook object or a worksheet object. In this section, I discuss two types
of events that are not associated with objects: time and keypresses.
Because time and keypresses aren’t associated with a particular object such
as a workbook or a worksheet, you program these events in a normal VBA
module (unlike the other events discussed in this chapter).