您可以使用MERGE语句和MATCH_RECOGNIZE来查找重叠：

MERGE INTO table_name t
USING (
  SELECT rowid AS rid,
         rn,
         MAX(enddate) OVER (PARTITION BY mn) AS enddate
  FROM   table_name
  MATCH_RECOGNIZE (
    PARTITION BY id, code
    ORDER BY startdate, enddate
    MEASURES
      COUNT(*) AS rn,
      MATCH_NUMBER() AS mn
    ALL ROWS PER MATCH
    PATTERN ( overlap* last_row )
    DEFINE overlap AS NEXT(startdate) <= MAX(enddate) + 1
  )
) m
ON (t.ROWID = m.rid)
WHEN MATCHED THEN
  UPDATE
  SET   enddate = m.enddate
  DELETE WHERE rn > 1

其中，对于样本数据：

CREATE TABLE table_name (id, code, startdate, enddate) AS
  SELECT 1, 'X', DATE '2023-01-01', DATE '2023-01-30' FROM DUAL UNION ALL
  SELECT 1, 'X', DATE '2023-02-01', DATE '2023-02-28' FROM DUAL UNION ALL
  SELECT 1, 'X', DATE '2023-02-10', DATE '2023-02-28' FROM DUAL UNION ALL
  SELECT 1, 'Y', DATE '2023-01-01', DATE '2023-01-31' FROM DUAL UNION ALL
  SELECT 1, 'Y', DATE '2023-02-01', DATE '2023-02-28' FROM DUAL UNION ALL
  SELECT 1, 'Y', DATE '2023-03-01', DATE '2023-03-31' FROM DUAL;

在MERGE之后，该表包含：
| ID|代码|开始日期|结束|
| --------------|--------------|--------------|--------------|
| 1| X| 2019 -01- 21 00：00：00| 2023-03-31 00：00：00|
| 1| X| 2019 -02- 21 00：00：00| 2019 -02-28 00：00：00|
| 1| Y轴|2019 -01- 21 00：00：00| 2023-03-31 00：00：00|
fiddle