取第一条数据的几种写法

SELECT  *
FROM    ( SELECT    * ,
                    r = ROW_NUMBER() OVER ( PARTITION BY MobilePhone ORDER BY MobilePhone )
          FROM      dbo.v_candidates
        ) t
WHERE   t.r = 1

class Student
{
   public string Name { get; set; }
   public int Score { get; set; }
}
List<Student> students = new List<Student>{
               new Student {Name="Terry", Score=50},          
               new Student {Name="Tom", Score=85},
               new Student {Name="Wade", Score=90},
               new Student {Name="James", Score=70},
               new Student {Name="Kobe", Score=90},
               new Student {Name="AK", Score=90}             
};

var query = from student in students
            orderby student.Score descending, student.Name
            select student;

var model=query.Where(m=>m.Name=='Tom').FirstOrDefault();
if(model!=null){
  //数据处理
}