Oracle 11g Release 2

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table your_table (fnm) as
select '4,37' from dual
union all
select '5,48' from dual;
2 rows affected

alter session set nls_numeric_characters = ',.';
-- fails as fnm ALIAS has . decimal character, session expects ,
select fnm as fnm_orig, replace(fnm, ',', '.') as fnm
from your_table
order by to_number(fnm, '99D99');
ORA-01722: invalid number

select fnm as fnm_orig, replace(fnm, ',', '.') as fnm
from your_table
order by to_number(fnm, '99D99', 'NLS_NUMERIC_CHARACTERS=.,');


FNM_ORIG
FNM


4,37
4.37

5,48
5.48


select fnm as fnm_orig, replace(fnm, ',', '.') as fnm
from your_table t
order by to_number(t.fnm, '99D99', 'NLS_NUMERIC_CHARACTERS=,.');


FNM_ORIG
FNM


4,37
4.37

5,48
5.48