oracle rownum分页出现重复数据

oracle rownum分页出现重复数据的情况：

一般情况是分组的字段不唯一导致的

解决办法:

原始sql：(错误的)

SELECT *
 FROM (
 SELECT a.*, ROWNUM r
 FROM hospital_inpatient_medication a
 WHERE  TO_CHAR(discharge_date,'YYYY-MM-DD HH24:MI:SS') BETWEEN '2024-01-01 00:00:00' AND '2024-02-01 00:00:00'
 AND  ROWNUM <= 500
 ORDER BY discharge_date asc 
)
WHERE r >= 1

改进：（正确的）

select *
from (
select row_.*, rownum rownum_
from ( select * from hospital_inpatient_medication
WHERE TO_CHAR(discharge_date,'YYYY-MM-DD HH24:MI:SS') BETWEEN '2024-02-01 00:00:00' AND '2024-03-01 00:00:00'
order by discharge_date asc, id asc )
row_ where rownum <= 5000) b
where b.rownum_ >=1

思路：就是加个唯一键分组