摘要

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在C#中使用LINQ（Language Integrated Query）进行数据排序是一种非常灵活和强大的方式。LINQ提供了多种排序方法，允许你对数据集合进行排序。最常用的排序方法是OrderBy、OrderByDescending、ThenBy和ThenByDescending。

正文

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操作符	描述	C#查询表达式语法
OrderBy	按升序操作排序值	orderby
OrderByDescending	降序排序操作值	orderby ... descending
ThenBy	执行二次排序按升序	orderby …, …
ThenByDescending	执行二次排序以降序	orderby …, … descending

一个例子

基础类

C#
class Hero
{
    public int HeroNo { get; set; }
    public string Name { get; set; }

    public int Age { get; set; }

    public Hero(string name, int age, int heroNo)
    {
        Name = name;
        Age = age;
        HeroNo = heroNo;
    }
}

调用

C#
private void btnSearch_Click(object sender, EventArgs e)
{
    List<Hero> heroes = new List<Hero>
    {
        new Hero("张飞",38,100),
        new Hero("刘备",40,101),
        new Hero("关羽",39,102),
        new Hero("曹操",45,103),
        new Hero("孙权",31,104)
    };

    var ret = from hero in heroes
              orderby hero.Age descending
              select hero;

    foreach (var item in ret)
    {
        lstMain.Items.Add(item.Name + " " + item.Age + " " + item.HeroNo);
    }
}

多个排序条件

C#
var ret = from hero in heroes
          orderby hero.Age, hero.HeroNo descending
          select hero;

试一下ThenByDescending

C#
private void btnSearch_Click(object sender, EventArgs e)
{
    List<Hero> heroes = new List<Hero>
    {
        new Hero("张飞",38,100),
        new Hero("刘备",40,101),
        new Hero("关羽",39,102),
        new Hero("曹操",45,103),
        new Hero("孙权",31,104),
        new Hero("黄忠",45,105),
    };

    var ret = heroes.AsQueryable().OrderBy(x => x.Age).ThenByDescending(x => x.HeroNo);

    foreach (var item in ret)
    {
        lstMain.Items.Add(item.Name + " " + item.Age + " " + item.HeroNo);
    }
}