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>22); 
   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=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"
        }
    }; 
    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