with subq as (
select substr(sales_date,1,7) as year_month
    ,sum(sales_AMT) as sales_AMT

from sales 
where UPDATED_NO is null
group by substr(sales_date,1,7)
)

,subq2 as (
select *
        ,sum(sales_AMT) over (order by year_month ROWS BETWEEN 11 PRECEDING AND CURRENT ROW) as idou
from subq
)

select year_month
        ,sales_AMT
        ,sum(sales_AMT) over (order by year_month) as cuml_amt
        ,idou
from subq2
where year_month >= '2023-01'