MsSql分区函数的使用

例１：根据Northwind数据库，要求查询出每个员工最近的三条订单数据

代码

1  with  result
2  as
3  (
4      select  row_number() over (partition  by  o.employeeID  order   by  o.orderdate  desc  ) as  row ,e.lastName,e.FirstName,o.OrderID
5      from  employees e  join  orders o  on  e.employeeID = o.employeeID
6  ) 
7 
8  select   *   from  result  where  row <= ３
9 

select e.firstname,e.lastname,ot.* from employees e 

cross apply (select top (2) * from orders o where o.employeeID=e.employeeID order by o.orderdate desc) as ot

order by e.employeeID

 

例２： 

代码

create   table  Student   -- 学生成绩表
(
 id  int ,   -- 主键
 Grade  int ,  -- 班级
 Score  int   -- 分数
)
insert  Student   select   1 , 1 , 88
union   all   select   2 , 1 , 66
union   all   select   3 , 1 , 75
union   all   select   4 , 2 , 30
union   all   select   5 , 2 , 70
union   all   select   6 , 2 , 80
union   all   select   7 , 2 , 60
union   all   select   8 , 3 , 90
union   all   select   9 , 3 , 70
union   all   select   10 , 3 , 80

select   *   from  student


select   top   3   with  ties  *   from   student  order   by  score  desc // 前三名

select   * ,row_number()  over (partition  by  grade  order   by  score  desc ) as   ' 名次 '   from  student