（1）利用Linq访问数组

  string[] s = new string[5]{"Leo","BackHam","David","Ronaldo","Roony"};
  var result = from s1 in s    //从数组S中选取
  where s1.Length > 3         //筛选条件是长度大于3
  orderby s1.ToString()        //根据内容排序
  select s1.ToString();         //展示内容

(2)利用Linq访问集合

    private List<Employee> GetEmploeeCollection()
        {
            List<Employee> e = new List<Employee>
           {
               new Employee(){ID="e1",Name="Tom",Age=23,Salary=34540},
               new Employee(){ID="e2",Name="Jim",Age=25,Salary=12230},
               new Employee(){ID="e3",Name="Bob",Age=33,Salary=87540},
               new Employee(){ID="e4",Name="Neo",Age=47,Salary=22112},
               new Employee(){ID="e5",Name="Leo",Age=54,Salary=52123},
               new Employee(){ID="e6",Name="David",Age=23,Salary=21222},
           };
           return e;
        }

       var result = from ep in GetEmploeeCollection()
                         where ep.Salary > 30000
                         orderby ep.Salary
                         select ep.Name;

（3）查询列的选取和格式化

var result = from ep in GetEmploeeCollection()
                         where ep.Salary > 30000
                         orderby ep.Salary
                         select new
                         {
                           name=ep.Name,               //显示员工名称
                           tax=ep.Salary*0.012        //显示个人所得税
                         };