WITH t AS
(
SELECT 1 seq, 100 code, 10000 amt FROM dual
UNION ALL SELECT 2, 200, 3000 FROM dual
UNION ALL SELECT 3, 901, 1000 FROM dual
UNION ALL SELECT 4, 300, 2000 FROM dual
UNION ALL SELECT 5, 400, 1000 FROM dual
UNION ALL SELECT 6, 902,  100 FROM dual
UNION ALL SELECT 7, 200,  400 FROM dual
UNION ALL SELECT 8, 901,  500 FROM dual
UNION ALL SELECT 9, 200, 1000 FROM dual
)
SELECT MIN(seq) min_seq
     , MAX(seq) max_seq
     , SUM(amt) amt
  FROM (SELECT seq, code, amt
             , SUM(flag) OVER(ORDER BY seq) grp
          FROM (SELECT seq, code, amt
                     , CASE WHEN code = 901 THEN 1
                            WHEN LAG(code) OVER(ORDER BY seq) = 902 THEN 1
                       ELSE 0 END flag
                  FROM t
                )
        )
 GROUP BY grp
HAVING MAX(code) IN (901, 902)
 ORDER BY grp
;

대단히 감사합니다..도움이 많이 되었습니다.