Question

我还在学习SQL Server，最近我遇到了排名问题（不确定我是否应该使用排名）。

我正在尝试将排名排序如下，但我无法通过在SQL服务器中使用row_number（over）或任何排名函数来实现。

[加入] table1中的内容有Cust_Code，Week和T_Mode，下面显示的是CustA。基本上我想知道CustA，他首先使用Air，然后Water在上周的时间里再次切换到Air。

**** Required Output ******
    Week    T_Mode  Rank
    201301  Air     1
    201303  Water   2
    201305  Water   2
    201306  Water   2
    201311  Air     3



i used Row_Number but it does not give what I want.

select *
, row_number()over(partition by T_Mode order by week) as Rank
from table1

the output returned

Week    T_Mode  Rank
201301  Air     1
201303  Water   1
201305  Water   2
201306  Water   3
201311  Air     2

任何建议都会受到欢迎。谢谢！

Answer 1

Declare @t table(Week1 int,T_Mode varchar(20))
insert into @t values(201301,'Air'),(201303,'Water'),(201305,'Water'),(201306,'Water'),(201311,'Air')

;with cte as
(
select top 1 week1,t_mode,1 [Rank] from @t order by week1
union all
select b.week1,b.t_mode,case when a.T_Mode=b.T_Mode then a.Rank else a.Rank+1   end  [Rank]  from @t b
outer apply cte a
where b.Week1>a.week1 and b.T_Mode<>a.T_Mode 


)

select distinct * from cte

Answer 2

这是一个适用于SQL Server 2012的解决方案：

select 
  week, t_mode, 
  sum(change) over (order by week rows unbounded preceding) [rank]

from (
  select *, 
  case when 
    (select top 1 t_mode 
     from table1 
     where week < t1.week 
     order by week desc) <> t1.t_mode then 1 else 0 end [change]

  from table1 t1
) x

请参阅this SQL Fiddle

这是SQL 2008的低效版本：

;with cte as (
  select *, 
  case when 
    (select top 1 t_mode 
     from table1 
     where week < t1.week 
     order by week desc) <> t1.t_mode then 1 else 0 end [change]

  from table1 t1
)

select 
  week, t_mode, 
  (select sum(change) from cte where week <= x.week) [rank]

from cte x

here's the fiddle。

SQL服务器按周排名功能

2 个答案: