By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
select
(extract(year from date '2021-03-01') - extract(year from date '2021-02-28')) * 31 * 12
+ (extract(month from date '2021-03-01') - extract(month from date '2021-02-28')) * 31
+ (extract(day from date '2021-03-01') - extract(day from date '2021-02-28'))
as diff
from dual;
| DIFF |
|---|
| 4 |