问题
I have this table:
id ID Date Cumulative
1 x Jan-10 10
3 x Feb-10 40
7 x Apr-10 60
9 x May-10 100
2 y Jan-10 20
6 y Mar-10 40
8 y Apr-10 60
10 y May-10 100
I need to Reverse the "Cumulative" in MS SQL Server Query to be as the following
id ID Date Cumulative Reversed
1 x Jan-10 10 10
3 x Feb-10 40 30
7 x Apr-10 60 20
9 x May-10 100 40
2 y Jan-10 20 20
6 y Mar-10 40 20
8 y Apr-10 60 20
10 y May-10 100 40
Note: query is for SQL Server 2012
回答1:
You can use lag to get the value in the previous row and subtract from the current row's value to get the reversed value.
select t.*, cumulative - coalesce(lag(cumulative) over(partition by id order by date),0) as reversed
from tablename t
From @Gordon Linoff's comment.. you can use lag(cumulative,1,0) instead of coalesce.
select t.*, cumulative-lag(cumulative,1,0) over(partition by id order by date) as reversed
from tablename t
回答2:
For below Sql server 2012 using recursive CTE
declare @t table(id int,IDs varchar(20),Dates varchar(20),Cumulative int)
insert into @t values
(1,'x','Jan-10', 10)
,(3,'x','Feb-10', 40)
,(7,'x','Apr-10', 60)
,(9,'x','May-10', 100)
,(2,'y','Jan-10', 20)
,(6,'y','Mar-10', 40)
,(8,'y','Apr-10', 60)
,(10,'y','May-10',100)
;With CTE as
(select *,row_number()over(partition by ids order by id)rn
from @t
)
,CTE1 as
(select id,ids,dates, Cumulative,rn,Cumulative Reversed
from cte where rn=1
union all
select c.id,c.ids,c.Dates,c.Cumulative,c.rn
,c.Cumulative-c1.Cumulative
from cte c
inner join cte c1 on c.ids=c1.ids
where c.rn=c1.rn+1
)
select * from cte1
来源：https://stackoverflow.com/questions/37058818/sql-server-reverse-running-total