column with unique value alowed to added only else violation

C

charles

i wont make a columne pf number if i add a new valew in a neww cell exicting
befor in this column one msg apear and the fot of this new cell chage to red
thaks
 
B

Bob Phillips

Private Sub Worksheet_Change(ByVal Target As Range)
Const WS_RANGE As String = "A:A" '<== change to suit

On Error GoTo ws_exit
Application.EnableEvents = False

If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
With Target
.Font.ColorIndex = xlColorIndexAutomatic
If Application.CountIf(Me.Columns(.Column), .Value) > 1 Then
MsgBox "duplicate value"
.Font.ColorIndex = 3
End If
End With
End If

ws_exit:
Application.EnableEvents = True
End Sub

'This is worksheet event code, which means that it needs to be
'placed in the appropriate worksheet code module, not a standard
'code module. To do this, right-click on the sheet tab, select
'the View Code option from the menu, and paste the code in.


--
---
HTH

Bob


(there's no email, no snail mail, but somewhere should be gmail in my addy)
 
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