WPF MVVM DataGrid Button Command绑定

<Button  Content="删除"
                                     Background="{StaticResource mainColor}"
                                     Width="90"
                                     Height="35"
                                     Style="{StaticResource BtnStyle}"
                                     Command="{Binding Path=DataContext.ExecuteDelDrugCommand,       
 RelativeSource= {RelativeSource FindAncestor,
  AncestorType={x:Type DataGrid}}}" />