상속: INotifyPropertyChanging, INotifyPropertyChanged
 partial void DeleteTask(Task instance);
 partial void UpdateTask(Task instance);
		private void detach_Tasks(Task entity)
		{
			this.SendPropertyChanging();
			entity.Section = null;
		}
 partial void InsertTask(Task instance);
		private void attach_Tasks(Task entity)
		{
			this.SendPropertyChanging();
			entity.Section = this;
		}