在Oracle 12中，您可以使用MATCH_RECOGNIZE进行逐行模式匹配：

SELECT *
FROM   table_name
MATCH_RECOGNIZE(
  ORDER BY shipment_date
  MEASURES
    SUM(qty) AS qty,
    LAST(shipment_date) AS shipment_date
  PATTERN (first_day within_two_days*)
  DEFINE
    within_two_days AS shipment_date <= FIRST(shipment_date) + INTERVAL '2' DAY
)

其中，对于样本数据：

CREATE TABLE table_name (Qty, shipment_date) AS
SELECT 10, DATE '2023-09-20' FROM DUAL UNION ALL
SELECT  8, DATE '2023-09-19' FROM DUAL UNION ALL
SELECT  3, DATE '2023-09-18' FROM DUAL UNION ALL
SELECT  5, DATE '2023-09-16' FROM DUAL UNION ALL
SELECT  2, DATE '2023-09-13' FROM DUAL;

输出：
| 数量|装运日期|
| --|--|
| 2 |2023-09-13 00：00：00|
| 8 |2023-09-18 00：00：00|
| 18 |2023-09-20 00：00：00：00|
fiddle