linq使用count与sum等

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("

---

用Count()得出查询结果的个数
");
var langCount = (from s in GetStudents()
select s.Language)
.Distinct()
.Count();
Response.Write(string.Format("

{0}

", langCount));
#endregion
#region 用Count()的Lambda表达式满足条件的元素个数
Response.Write("

---

用Count()得出查询结果的个数
");
var ageCoun = (from s in GetStudents()
select s.Age)
.Count(a=>a>22);
Response.Write(string.Format("

{0}

", ageCoun));
#endregion
#region 用Sum()将查询结果相加
Response.Write("

---

用Sum()将查询结果相加
");
var ageSum = (from s in GetStudents()
select s.Age)
.Sum();
//var ageSum = GetStudents().Sum(s=>s.Age);
Response.Write(string.Format("

{0}

", ageSum));
#endregion
#region 用Min()得出查询结果的最小值
Response.Write("

---

用Min()得出查询结果的最小值
");
var ageMin = (from s in GetStudents()
select s.Age)
.Min();
//var ageMin = GetStudents().Min(s => s.Age);
Response.Write(string.Format("

{0}

", ageMin));
#endregion
#region 用Max()得出查询结果的最大值
Response.Write("

---

用Max()得出查询结果的最大值
");
var ageMax = (from s in GetStudents()
select s.Age)
.Max();
//var ageMax = GetStudents().Max(s => s.Age);
Response.Write(string.Format("

{0}

", ageMax));
#endregion
#region 用Average()得出查询结果的平均值
Response.Write("

---

用Average()得出查询结果的平均值
");
var ageAverage = (from s in GetStudents()
select s.Age)
.Average();
//var ageAverage = GetStudents().Average(s => s.Age);
Response.Write(string.Format("

{0}

", ageAverage));
#endregion
}
#region 构造一个学生集合体
private List GetStudents()
{
List students = new List {
new Student{ Name="YOUNG", Age=25, Language="Chinese"},
new Student{ Name="JESSIE", Age=21, Language="Scotland"},
new Student{ Name="KELLY", Age=18, Language="English"},
new Student{ Name="JUNE", Age=20, Language="English"},
new Student{ Name="ADRIAN", Age=22, Language="Italy"},
new Student{ Name="BRUCE", Age=17, Language="Scotland"},
new Student{ Name="BRANT", Age=30, Language="Germany"},
new Student{ Name="BEN", Age=25, 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