Вы можете использовать TO_CHAR
и TO_DATE
следующим образом:
SQL> WITH YOUR_DATE ( DT ) AS ( -- your data
2 SELECT 202001 FROM DUAL
3 )
4 -- your query
5 SELECT TO_CHAR(TO_DATE(DT,'YYYYMM'), 'Mon-YYYY') AS RESULT FROM YOUR_DATE;
RESULT
--------
Jan-2020
SQL>
Cheers !!