선입선출이라면?
결과가 이상한데요?
최신 자재만 908 이 남아야 할 것 같은데.
3년전 자재가 408 이 남아 있네요?
과거 자재부터 출고되어야 하는데 과거자재를 남기고 최신자재를 출고한다는 의미가 되는데요?

WITH t AS
(
SELECT '201701' ym, 'A' cd, 176 s, 0 i, 0 o, 176 e
UNION ALL SELECT '201702', 'A',  176, 1032,   12, 1196
UNION ALL SELECT '201703', 'A', 1196,    0,    0, 1196
UNION ALL SELECT '201704', 'A', 1196,    0,    0, 1196
UNION ALL SELECT '201705', 'A', 1196,    8,   16, 1188
UNION ALL SELECT '201706', 'A', 1188,    0,    0, 1188
UNION ALL SELECT '201707', 'A', 1188,   40,   80, 1148
UNION ALL SELECT '201708', 'A', 1148,   20,   40, 1128
UNION ALL SELECT '201709', 'A', 1128,   64,   64, 1128
UNION ALL SELECT '201710', 'A', 1128,    0,    0, 1128
UNION ALL SELECT '201711', 'A', 1128,   40,  144, 1024
UNION ALL SELECT '201712', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201801', 'A', 1024,   80,   80, 1024
UNION ALL SELECT '201802', 'A', 1024, 1536, 1536, 1024
UNION ALL SELECT '201803', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201804', 'A', 1024,  120,  120, 1024
UNION ALL SELECT '201805', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201806', 'A', 1024,  560,  560, 1024
UNION ALL SELECT '201807', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201808', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201809', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201810', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201811', 'A', 1024,   24,   24, 1024
UNION ALL SELECT '201812', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201901', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201902', 'A', 1024,    0,    0, 1024
UNION ALL SELECT '201903', 'A', 1024,   40,   40, 1024
UNION ALL SELECT '201904', 'A', 1024,  180,  200, 1004
UNION ALL SELECT '201905', 'A', 1004,    0,    0, 1004
UNION ALL SELECT '201906', 'A', 1004,    0,    0, 1004
UNION ALL SELECT '201907', 'A', 1004,    0,    0, 1004
UNION ALL SELECT '201908', 'A', 1004,  176,  176, 1004
UNION ALL SELECT '201909', 'A', 1004,    0,    0, 1004
UNION ALL SELECT '201910', 'A', 1004,   40,   40, 1004
UNION ALL SELECT '201911', 'A', 1004,   48,   48, 1004
UNION ALL SELECT '201912', 'A', 1004,  192,  288,  908
UNION ALL SELECT '202001', 'A',  908,   80,   80,  908
UNION ALL SELECT '202002', 'A',  908,    0,    0,  908
UNION ALL SELECT '202003', 'A',  908,   80,   80,  908
UNION ALL SELECT '202004', 'A',  908,   80,   80,  908
UNION ALL SELECT '202005', 'A',  908, 1240, 1240,  908
UNION ALL SELECT '202006', 'A',  908,    0,    0,  908
UNION ALL SELECT '202007', 'A',  908,    0,    0,  908
UNION ALL SELECT '202008', 'A',  908,   80,   80,  908
UNION ALL SELECT '202009', 'A',  908,   80,   80,  908
UNION ALL SELECT '202010', 'A',  908,  112,  112,  908
)
SELECT cd
     , ISNULL(SUM(CASE y WHEN 0 THEN v END), 0) "1년미만"
     , ISNULL(SUM(CASE y WHEN 1 THEN v END), 0) "1년~2년"
     , ISNULL(SUM(CASE y WHEN 2 THEN v END), 0) "2년~3년"
     , ISNULL(SUM(CASE y WHEN 3 THEN v END), 0) "3년이상"
  FROM (SELECT cd
             , y
             , CASE WHEN i_sum <= e_last THEN i ELSE e_last - i_sum + i END v
          FROM (SELECT ym, cd, s, i, o, e
                     , DATEDIFF( mm
                       , CAST(CONCAT(ym      , '01') AS DATE)
                       , CAST(CONCAT('202010', '01') AS DATE)
                       ) / 12 y
                     , SUM(i) OVER(ORDER BY ym DESC) i_sum
                     , MIN(CASE WHEN ym = '202010' THEN e END) OVER() e_last
                  FROM t
                 WHERE ym <= '202010'
                ) a
         WHERE i_sum - i < e_last
           AND i > 0
        ) a
 GROUP BY cd
;