with
    m(YM, part_mrr) as
    (
        select
            min(MONTHLY), 0
        from 
            MRR_DATA
        union
        select
            DATE(MONTHLY, '+1 month'),
            NEW_MRR
            + EXPANSION_MRR
            - DOWNGRADE_MRR
            - CHURN_MRR
        from
            MRR_DATA
    )
select
    m1.YM
    ,sum(m2.part_mrr) as MRR
from
    m as m1
inner join m as m2
on m1.YM >= m2.YM
group by m1.YM
;