LINQ to List泛型的几种简单查询(转：http://www.189works.com/article-43804-1.html)

来源：互联网发布：java replaceall 空格编辑：程序博客网时间：2024/06/07 02:48

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：