WITH t AS
(
SELECT 1 day, 'a' apno, 10 cost, 1 qty FROM dual
UNION ALL SELECT  2, 'a', 10, 2 FROM dual
UNION ALL SELECT  3, 'a', 10, 3 FROM dual
UNION ALL SELECT  4, 'a', 10, 4 FROM dual
UNION ALL SELECT  5, 'a', 10, 5 FROM dual
UNION ALL SELECT 10, 'a', 12, 6 FROM dual
UNION ALL SELECT 11, 'a', 12, 7 FROM dual
UNION ALL SELECT 20, 'a', 10, 8 FROM dual
UNION ALL SELECT 30, 'a', 10, 9 FROM dual
)
SELECT apno
     , MAX(day) day
     , cost
     , SUM(qty) qty
     , cost * SUM(qty) amt
  FROM (SELECT day, apno, cost, qty
             , ROW_NUMBER() OVER(PARTITION BY apno ORDER BY day)
             - ROW_NUMBER() OVER(PARTITION BY apno, cost ORDER BY day) gb
          FROM t
        )
 GROUP BY apno, cost, gb
 ORDER BY apno, day
;

역시 대단하십니다.

감사합니다. ^^