取第一条数据的几种写法

1. SQL

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

2. LINQ

   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
   }