with month as
(
	select MONTHLY
	from MRR_DATA
	union 
	select date(MONTHLY, '+1 months')
	from MRR_DATA
	where MONTHLY = (select max(MONTHLY) from MRR_DATA))
, mrr_cal as
(
	select
		MONTHLY,
		NEW_MRR+EXPANSION_MRR-DOWNGRADE_MRR-CHURN_MRR as MRR
	from
		MRR_DATA
)
select
	mon.MONTHLY as YM,
	SUM(IFNULL(mc.MRR, 0)) as MRR
from
	month mon
	left outer join mrr_cal mc
	on  mc.MONTHLY <= date(mon.MONTHLY, '-1 months')
group by
    mon.MONTHLY