SELECT DBTIMEZONE FROM DUAL;

------------------------------
+00:00



SELECT * FROM SYS.DATABASE_PROPERTIES;

--------------- ------- -----------------
DBTIMEZONE	+00:00	DB time zone




ALTER DATABASE SET TIME_ZONE='+09:00'; -- 서버 재시작 해야함




SELECT * FROM SYS.DATABASE_PROPERTIES;

--------------- ------- -----------------
DBTIMEZONE	+09:00	DB time zone




SELECT DBTIMEZONE FROM DUAL;

------------------------------
+09:00