select t1.MONTHLY as YM
    ,t2.MRR + t2.NEW_MRR + t2.EXPANSION_MRR - t2.DOWNGRADE_MRR - t2.CHURN_MRR as MRR
from MRR_DATA t1
    join (
        select MONTHLY, NEW_MRR, EXPANSION_MRR, DOWNGRADE_MRR, CHURN_MRR
            ,(NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR) as MRR
        from MRR_DATA
        union all
        select 
            date(min(MONTHLY), '-1 months') as MONTHLY
            ,0 as NEW_MRR
            ,0 as EXPANSION_MRR
            ,0 as DOWNGRADE_MRR
            ,0 as CHURN_MRR
            ,0 as MRR
        from MRR_DATA
    ) t2
        on t1.MONTHLY = date(t2.MONTHLY, '+1 months')
order by t1.MONTHLY