Diffenrence between NLS_UPPER and UPPER

Question

I am new in PL/SQL Language. I saw there were 2 functions in PL/SQL: UPPER and NLS_UPPER. They both do the same thing. I want to know the difference between of these functions. thanks

Answer 1

NLS_UPPER knows about locale specific rules

This query:

select nls_upper('ß', 'NLS_SORT = XGerman') as upper1, 
       upper('ß') as upper2
from dual;

returns the following:

UPPER1 | UPPER2
-------+-------
SS     | ß     

see the difference?