Imports System.Data
Public Class frmTableCellFormatting
    Dim dt As New DataTable
    Private Sub frmTableCellFormatting_Load(ByVal sender As Object, _
                                ByVal e As System.EventArgs) Handles Me.Load
        With dt
            .Columns.Add("Nr.")
            With .Columns(0)
                .AllowDBNull = True
                .DataType = GetType(Decimal)
                .DefaultValue = DBNull.Value
            End With
 
            For i As Integer = 0 To 10
                Dim r As DataRow = .NewRow
                If i Mod 2 = 0 Then r.Item(0) = i
                .Rows.Add(r)
            Next i
        End With
        DataGridView1.DataSource = dt
    End Sub
 
    Private Sub DataGridView1_DataError(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) _
    Handles DataGridView1.DataError
        If e.ColumnIndex = 0 Then
            MsgBox("Wenn Sie einen Wert in diese Spalte eintragen möchten, " & _
                "muss es ein Dezimalbruch sein", MsgBoxStyle.Information)
            e.Cancel = True
        End If
    End Sub
End Class