Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 1 Then
If IsEmpty(Target) Then Exit Sub
derlin = Range('A65536').End(xlUp).Row
For n = 2 To derlin - 1
If Target.Value = Cells(n, 1) Then
Cells(n, 1).Select
MsgBox (' ce code existe deja ici')
End If
Next n
End If
If Target.Column = 2 Then
If IsEmpty(Target) Then Exit Sub
derlin = Range('B65536').End(xlUp).Row
For n = 2 To derlin - 1
If Target.Value = Cells(n, 2) Then
Cells(n, 2).Select
MsgBox (' cette designation existe deja ici')
End If
Next n
End If
End Sub