如何将UserControl上的按钮绑定到父控件中的命令？

public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(
    "Command", typeof(ICommand), typeof(UserControlName), new PropertyMetadata(null));

public ICommand Command
{
    get { return (ICommand)GetValue(CommandProperty); }
    set { SetValue(CommandProperty, value); }
}

<Button Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:UserControlName}}, Path=Command}" Content="按钮内容" />

<local:UserControlName Command="{Binding ParentCommand}" />