But using that format also I am getting below error,

SQL> SQL> SQL> SQL> 2 3 4 5 6 7 8 9 10 11 12 13 TO_DATE (20100913,"YYYYMMDD")
*
ERROR at line 10:
ORA-06550: line 10, column 23:
PL/SQL: ORA-00984: column not allowed here
ORA-06550: line 3, column 1:
PL/SQL: SQL Statement ignored