Inserting year with zero
SQL&gt; create table t1 (c1 date);

Table created.

SQL&gt; insert into t1 values (date'0000-01-05');

1 row created.

SQL&gt; commit;

Commit complete.

SQL&gt; select c1, to_char(c1, 'dd/MM/yyyy'), dump(c1) from t1;

C1                  TO_CHAR(C1
------------------- ----------
DUMP(C1)
--------------------------------------------------------------------------------
0000-01-05 00:00:00 00/00/0000
Typ=12 Len=7: 100,100,1,5,1,1,1