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sql-server - 将一行与前 12 个值进行比较

问题描述

我正在尝试将一个值与前 12 个月/12 行进行比较。如果过去 12 个月的值为“是”，则第 12 行为“是”。对于每一行也是如此（比较前 12 个值）。

我正在按照以下方式进行操作。它可以工作，但我必须为多个列执行此操作，因此代码将非常冗长。

有什么方法可以通过简单的步骤完成 n 列吗？

select *,
--Identify customers who have applied for principal relief within the past 12 months
 lag(PrincipalReliefFlag,1)  over(partition by id,productcode order by snapshot_date) PRflg1
,lag(PrincipalReliefFlag,2)  over(partition by id,productcode order by snapshot_date) PRflg2
,lag(PrincipalReliefFlag,3)  over(partition by id,productcode order by snapshot_date) PRflg3
,lag(PrincipalReliefFlag,4)  over(partition by id,productcode order by snapshot_date) PRflg4
,lag(PrincipalReliefFlag,5)  over(partition by id,productcode order by snapshot_date) PRflg5
,lag(PrincipalReliefFlag,6)  over(partition by id,productcode order by snapshot_date) PRflg6
,lag(PrincipalReliefFlag,7)  over(partition by id,productcode order by snapshot_date) PRflg7
,lag(PrincipalReliefFlag,8)  over(partition by id,productcode order by snapshot_date) PRflg8
,lag(PrincipalReliefFlag,9)  over(partition by id,productcode order by snapshot_date) PRflg9
,lag(PrincipalReliefFlag,10) over(partition by id,productcode order by snapshot_date) PRflg10
,lag(PrincipalReliefFlag,11) over(partition by id,productcode order by snapshot_date) PRflg11
into #test
from #temp

select *
,case when (PrincipalReliefFlag='Y' or PRflg1='Y' or PRflg2='Y' or PRflg3='Y' or PRflg4='Y' or PRflg5='Y' or PRflg6='Y' or PRflg7='Y' or PRflg8='Y' or PRflg9='Y' or PRflg10='Y' or  PRflg11='Y')
    then  'Y' 
    when (PrincipalReliefFlag='N' 
                                and (PRflg1='N' or PRflg1 is null)  
                                and (PRflg2='N' or PRflg2 is null) 
                                and (PRflg3='N' or PRflg3 is null) 
                                and (PRflg4='N'  or PRflg4 is null)
                                and (PRflg5='N' or PRflg5 is null)
                                and (PRflg6='N' or  PRflg6 is null)
                                and (PRflg7='N' or PRflg7 is null)
                                and (PRflg8='N' or  PRflg8  is null)
                                and (PRflg9='N' or PRflg9 is null)
                                and (PRflg10='N' or PRflg10 is null)
                                and (PRflg11='N' or PRflg11 is null) )
    then 'N'
    end PrincipalRelief_applied_in_last12m
from #test

期待简单的步骤。也尝试使用连接，但无法成功。

标签： sql-serversas

解决方案

这是你想要的吗？

select t.*,
       max(PrincipalReliefFlag) over (partition by id, productcode
                                      order by snapshot_date
                                      rows between 11 preceding and current row
                                     ) as PrincipalReliefFlag_12
from #temp t;

这将采用 12 个月期间的最大值 - 如果标志仅采用 和 的值，则将'Y'起作用'N'。

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