with  test as (
select MONTHLY,0 as MRR from MRR_DATA
union all
select a.MONTHLY,b.NEW_MRR + b.EXPANSION_MRR - b.DOWNGRADE_MRR - b.CHURN_MRR as MRR from MRR_DATA a join MRR_DATA b on a.MONTHLY > b.MONTHLY )

select YM, MRR from
(
select MONTHLY as YM,sum(MRR) MRR from  test 
group by MONTHLY
)
order by YM asc