这是我的桌子。
Price Volume Month
--------------------------
600 60 April
500 50 April
450 0 April
400 0 April
300 40 April
95 0 April
200 40 March
100 40 March
90 0 March
80 0 March
70 10 March
60 0 March
对于每个月，我需要选择Volume列中前两个连续零之前的所有行，该列按价格按降序排序。例如这是我想得到的：
Price Volume Month rn
--------------------------------
600 60 April 0
500 50 April 0
200 40 March 0
100 40 March 0
我知道如何在没有按月分组的情况下完成它（感谢stackoverflow.com link）。
这是代码：
with
flagged as (
select price,
volume,
case
when volume + lead(volume) over (order by price desc) = 0 then 1
else 0
end as rn, month
from [AnalysisDatabase].[dbo].[tblLagExample]),
counted as (
select price,
volume,
sum(rn) over (order by price desc) as cn ,-- this is running sum
rn, month
from flagged)
select price, volume, cn, month, rn
from counted
where cn = 0 and rn = 0
order by price desc
有关如何按月分组的建议。