Convert 'DD-MM-YY' to 'Month Year' oracle - sql

Question

I have a date a field that displays date in the format '19-JAN-20' I would like to display it as 'January 2019' using oracle database.
select '19-JAN-19' FROM DUAL

Answer 1

You need to use TO_CHAR to display in the required format:
select to_char(DATE '2019-01-20', 'Month YYYY') dt from dual;
DT
-------------
January 2019
select '19-JAN-19' FROM DUAL
There are couple of issues with that statement:
'19-JAN-19' is a string, not a date. Always use TO_DATE to explicitly convert it to date, or stick to ANSI date literal like I used in my demo.
Do not use two-digit YY representation for year, that's the reason Y2K bug was introduced. Always use YYYY.

Answer 2

Looks like a nested TO_CHAR, if "date" value you mentioned - 19-JAN-20 is stored as a string:
SQL> with test (col) as
2 (select '19-JAN-20' from dual)
3 select
4 to_char(
5 to_date(col, 'dd-mon-yy', 'nls_date_language = english'),
6 'fmMonth yyyy', 'nls_date_language = english'
7 ) result
8 from test;
RESULT
--------------
January 2020
SQL>
If your database speaks English, you can omit the NLS_DATE_LANGUAGE part (mine speaks Croatian so I included it).
However, if it is a date you'd just want to display differently, then:
(Just to avoid NLS_DATE_LANGUAGE in TO_DATE):
SQL> alter session set nls_date_language = 'english';
Session altered.
Default format in my database:
SQL> select sysdate from dual;
SYSDATE
--------
08.06.20
Alter session to desired format:
SQL> alter session set nls_date_format = 'fmMonth yyyy';
Session altered.
SQL> select sysdate from dual;
SYSDATE
--------------
June 2020
Or, apply TO_DATE function with desired format mask:
SQL> select to_char(sysdate, 'fmMonth yyyy') result from dual;
RESULT
--------------
June 2020
SQL>