SELECT T1.MONTHLY,
       IFNULL(T2.MRR,0) AS MRR
  FROM MRR_DATA T1 LEFT JOIN (SELECT MONTHLY,(NEW_MRR + EXPANSION_MRR - DOWNGRADE_MRR - CHURN_MRR) AS MRR 
                                FROM MRR_DATA
                             ) T2
                     ON DATETIME(T1.MONTHLY,'-1 MONTHS') = DATETIME(T2.MONTHLY,'0 MONTHS')
                   INNER JOIN (SELECT MIN(MONTHLY) AS MIN_MONTH,
                                      MAX(MONTHLY) AS MAX_MONTH
                                 FROM MRR_DATA) T3
                     ON T1.MONTHLY BETWEEN T3.MIN_MONTH AND T3.MAX_MONTH