LINQ to List泛型的几种简单查询

最近比较喜欢LINQ，真是碉堡了。下面写了个例子演示一下LINQ对List<T>的操作，包括排序、where条件、选部分数据等查询。最近偷懒，不写注释了，大家自己看一下就明白了～

测试用的BLL和Model

public class TestBLL
{
    public List<TestModel> GetList()
    {
        return new List<TestModel>()
        {
            new TestModel(){ Id=1, Name="RYWE", Content="IOJADJ", Posttime=DateTime.Now.AddHours(1) },
            new TestModel(){ Id=2, Name="JGFA", Content="CAFYRE", Posttime=DateTime.Now.AddHours(0) },
            new TestModel(){ Id=4, Name="PIOU", Content="OVXZLA", Posttime=DateTime.Now.AddHours(5) },
            new TestModel(){ Id=5, Name="OUIH", Content="AIPJLM", Posttime=DateTime.Now.AddHours(3) },
            new TestModel(){ Id=7, Name="ZCXI", Content="KUQOPA", Posttime=DateTime.Now.AddHours(7) }
        };
    }
}

public class TestModel
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Content { get; set; }
    public DateTime Posttime { get; set; }

    public TestModel()
    {
    }

    public override string ToString()
    {
        StringBuilder sb = new StringBuilder();
        sb.Append(String.Format("{0}={1}, ", "Id", this.Id));
        sb.Append(String.Format("{0}={1}, ", "Name", this.Name));
        sb.Append(String.Format("{0}={1}, ", "Content", this.Content));
        sb.Append(String.Format("{0}={1}", "Posttime", this.Posttime));
        return sb.ToString();
    }
}

测试代码：

static void Main(string[] args)
{

    TestBLL bll = new TestBLL();
    List<TestModel> mList = bll.GetList();

    var query = from m in mList
                select m;

    var query1 = from m in mList
                 where m.Id > 2
                 select m;

    var query2 = from m in mList
                 where m.Id > 2
                 orderby m.Id descending 
                 select m;

    var query3 = from m in mList
                 orderby m.Posttime descending
                 select m;

    var query4 = (from m in mList 
                 select m).Take(3);

    var query5 = from m in mList
                 orderby m.Name ascending
                 select m;

    PrintList("from m in mList select m", query);
    PrintList("from m in mList where m.Id > 2 select m", query1);
    PrintList("from m in mList select m", query2);
    PrintList("from m in mList orderby m.Posttime descending select m", query3);
    PrintList("(from m in mList where select m).Take(3)", query4);
    PrintList("from m in mList orderby m.Name ascending select m", query5);

    Console.ReadKey();

}

private static void PrintList(string expression, IEnumerable<TestModel> query)
{
    Console.WriteLine("Query expression: " + expression);
    Console.WriteLine("__________________________________________________________________");
    foreach (var item in query)
    {
        Console.WriteLine(item.ToString());
    }
    Console.WriteLine("\n");
}

有图有真相：