using System;

using System.Data;

using System.Configuration;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Text;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Collections.Generic;

using System.Collections;

public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        #region 用Count()得出查询结果的个数

        Response.Write("<hr>用Count()得出查询结果的个数<br>");

        var langCount = (from s in GetStudents()

                           select s.Language)

                           .Distinct()

                           .Count();

        Response.Write(string.Format("<div class='result'>{0}</div>", langCount));

        #endregion

        #region 用Count()的Lambda表达式满足条件的元素个数

        Response.Write("<hr>用Count()得出查询结果的个数<br>");

        var ageCoun = (from s in GetStudents()

                          select s.Age)

                          .Count(a=>a>);

        Response.Write(string.Format("<div class='result'>{0}</div>", ageCoun));

        #endregion

        #region 用Sum()将查询结果相加

        Response.Write("<hr>用Sum()将查询结果相加<br>");

        var ageSum = (from s in GetStudents()

                      select s.Age)

                       .Sum();

        //var ageSum = GetStudents().Sum(s=>s.Age);

        Response.Write(string.Format("<div class='result'>{0}</div>", ageSum));

        #endregion

        #region 用Min()得出查询结果的最小值

        Response.Write("<hr>用Min()得出查询结果的最小值<br>");

        var ageMin = (from s in GetStudents()

                      select s.Age)

                       .Min();

        //var ageMin = GetStudents().Min(s => s.Age);

        Response.Write(string.Format("<div class='result'>{0}</div>", ageMin));

        #endregion

        #region 用Max()得出查询结果的最大值

        Response.Write("<hr>用Max()得出查询结果的最大值<br>");

        var ageMax = (from s in GetStudents()

                      select s.Age)

                       .Max();

        //var ageMax = GetStudents().Max(s => s.Age);

        Response.Write(string.Format("<div class='result'>{0}</div>", ageMax));

        #endregion

        #region 用Average()得出查询结果的平均值

        Response.Write("<hr>用Average()得出查询结果的平均值<br>");

        var ageAverage = (from s in GetStudents()

                      select s.Age)

                      .Average();

        //var ageAverage = GetStudents().Average(s => s.Age);

        Response.Write(string.Format("<div class='result'>{0}</div>", ageAverage));

        #endregion

    }

    #region 构造一个学生集合体

    private List<Student> GetStudents()

    {

        List<Student> students = new List<Student> {

             new Student{ Name="YOUNG", Age=, Language="Chinese"},

             new Student{ Name="JESSIE", Age=, Language="Scotland"},

             new Student{ Name="KELLY", Age=, Language="English"},

             new Student{ Name="JUNE", Age=, Language="English"},

             new Student{ Name="ADRIAN", Age=, Language="Italy"},

             new Student{ Name="BRUCE", Age=, Language="Scotland"},

             new Student{ Name="BRANT", Age=, Language="Germany"},

             new Student{ Name="BEN", Age=, Language="Chinese"}

        };

        return students;

    }

    #endregion

}

#region 学生类

class Student

{

    public int Age { get; set; }

    public string Name { get; set; }

    public string Language { get; set; }

}

#endregion