Linq查询Count、Sum、Min、Max、Average

原文地址：Linq——Count、Sum、Min、Max、Average作者：mousekitty

Linq查询之Count、Sum、Min、Max、Average

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;

　　#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"
        }
    };
    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