with 
FIRST_MRR as (
select
    MONTHLY as YM
    ,0 as MRR_ADD
from
    MRR_DATA
order by 1 limit 1
)


,MRR_ADD as (
select
    YM
    ,MRR_ADD
from
    FIRST_MRR
union all
select
    date(MONTHLY, '+1 month') as YM
    ,NEW_MRR+EXPANSION_MRR-DOWNGRADE_MRR-CHURN_MRR
from
    MRR_DATA

)


,MRR_ADD2 as (
select
    P.YM
    ,P.MRR_ADD
    ,coalesce(S.MRR_ADD, 0) as MRR_ADD2
from
    MRR_ADD P
    left outer join
        MRR_ADD S
        on
            P.YM > S.YM
            
)


select
    YM
    ,MRR_ADD + sum(MRR_ADD2) as MRR
from
    MRR_ADD2
group by 1
order by 1
;