SQL> select to_char(trunc(sysdate), 'yyyy/mm/dd') A from dual;

A
----------
2007/10/19

SQL>
SQL>
SQL> select to_date(sysdate, 'yyyy/mm/dd') A from dual;

A
---------
07-OCT-19

SQL> select sysdate from dual;

SYSDATE
---------
19-OCT-07

SQL> select to_date('24-MAY-07', 'DD-MM-YY') from dual;

TO_DATE('
---------
24-MAY-07


SQL> select to_char(sysdate,'YY/MM/DD') from dual;

TO_CHAR(
--------
07/10/26