Select To_Char(to_date('31-Mar-2020'), 'Wth') As A, To_Char(to_date('31-Mar-2020'), 'WTH') As B, 
       To_Char(to_date('01-Feb-2020'), 'WWth') As C, To_Char(to_date('01-Feb-2020'), 'WWTH') As D
from dual;

Ouput

A B C D
5th 5TH 05TH 05TH

--Expected Output--
th in A's output is in small letter. [Expected]
TH in B's output is in capital letter. [Expected]

--Unexpected Output--
TH in C's output is in Capital letter. [Not expected]
TH in D's output is in capital letter. [Expected]


Question: For C column I deliberately wrote 'WWth' to get "th" in small letter but it is showing "TH" which is unexpected output which is against format model.

SQL> select to_char(sysdate,'DDth') from dual;

TO_C
----
17TH

SQL> select to_char(sysdate,'ddth') from dual;

TO_C
----
17th