问如果输入日期不可用，则如何获取oracle中开始日期和结束日期之间的输入日期，然后返回最大日期记录

EN

WITH data AS
 (SELECT DATE '2020-08-14' input FROM dual) --input parameter 
SELECT arng_id,st_dt,end_dt
FROM   (SELECT input
              ,demo.*
              ,MAX(end_dt) over(ORDER BY NULL) max_dt --taken max(end_dt) to match in case no result with input parameter
        FROM   demo
              ,data)
WHERE  (input BETWEEN st_dt AND end_dt)  -- matches with input paramater OR
OR     (max_dt BETWEEN end_dt AND input) -- condition when no result with first match 
ORDER  BY end_dt DESC -- order by require to fetch the max record always
FETCH  FIRST 1 ROW ONLY --oracle 12c feature