Private Sub TextBox9_Validated(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles TextBox9.Validated
        Dim z As Integer 
        If Integer.TryParse( TextBox9.Text, z ) Then
          TextBox9.Text = z.ToString("N2")
        Else
 ' Fehlermeldung
        End If
    End Sub

 
  Dim cmd as New MySqlCommand( "INSERT INTO TableName ( Wert1, Wert2 ) VALUES (" & _
    "?Wert1, ?Wert2)")
cmd.Parameters.AddWithValue( "?Wert1", IntWert )
cmd.Parameters.AddWithValue( "?Wert2", doubleWert )
...