with
	tan as (
		select
			monthly
			,new_mrr + expansion_mrr - downgrade_mrr - churn_mrr as tan_mrr
		from
			mrr_data
		)
	,next as (
		select
			date(monthly, '+1 months') as next_month
			,sum(tan_mrr) over (order by monthly) as ruiseki
		from
			tan
	)
	,ym as (
		select
			monthly as ym
		from
			mrr_data
		union
		select
			date(monthly, '+1 months') as ym
		from
			mrr_data
	)
	,t as (
		select
			ym.ym as YM
			,next.ruiseki as MRR
		from
			ym
		left join
			next
			on
				ym.ym = next.next_month
	)

select
	YM
	,case
		when MRR is null then 0
		else MRR
		end as MRR
from
	t