with diff as (
select
    date(MONTHLY,"+1 month") as YM
    ,NEW_MRR+EXPANSION_MRR-DOWNGRADE_MRR-CHURN_MRR as MRR_DIFF
from
    MRR_DATA
)
,base(YM,MRR) as (
    select 
        (select min(MONTHLY) from MRR_DATA)
        ,0
    union all
    select
        date(YM,"+1 month")
        ,MRR +MRR
    from
    base
)
select * from base