问将数据保存在XML和数据库中哪个更好？

EN

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication2
{
    [Serializable()]
    public class Child
    {
        public string Property1 { get; set; }
    }

    [Serializable()]
    public class TestClass
    {

        public int Property1 { get; set; }
        public string Property2 { get; set; }
        public DateTime Property3 { get; set; }
        public Child Child { get; set; }
    }


    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            TestClass testClass = new TestClass()
            {
                Property1 = 1,
                Property2 = "test",
                Property3 = DateTime.Now,
                Child = new Child()
                {
                     Property1 = "test", 
                }
            };

            System.Runtime.Serialization.Formatters.Binary.BinaryFormatter formatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
            System.IO.MemoryStream memoryStream = new System.IO.MemoryStream();
            formatter.Serialize(memoryStream, testClass);

            memoryStream.Position = 0;
            TestClass deserialized = formatter.Deserialize(memoryStream) as TestClass;
        }
    }
}