You may wonder why between these dates only one day:
SQL> select date'1582-10-15'-date'1582-10-04' from dual;
DATE'1582-10-15'-DATE'1582-10-04'
---------------------------------
1
SQL> select date'1582-10-05' "dt_1"
2 ,date'1582-10-05' + 1 "dt_1 + 1"
3 ,date'1582-10-05' - 1 "dt_1 - 1"
4 ,to_date('1582-10-05','yyyy-mm-dd') "dt_1 and to_date"
5 from dual;
dt_1 dt_1 + 1 dt_1 - 1 dt_1 and to_date
------------------ ------------------ ------------------ ------------------
October 05, 1582 October 16, 1582 October 04, 1582 October 15, 1582
Over the last 2 months, I gave link to answer several times, so i decided to post it here: http://www.orafaq.com/papers/dates_o.doc
BTW, yet another trick:
SQL> select date'0000-02-29','to_char:'||date'0000-02-29' from dual;
DATE'0000-02-29' 'TO_CHAR:'||DATE'0000-02-29'
------------------- ---------------------------
29.02.0000 00:00:00 to_char:00.00.0000 00:00:00
SQL> select to_date('0000-02-29','yyyy-mm-dd') error from dual;
select to_date('0000-02-29','yyyy-mm-dd') error from dual
*
ERROR at line 1:
ORA-01841: (full) year must be between -4713 and +9999, and not be 0