Character fields don't have format. You'll have to do that in a query (or create a formula column). Here's an example: SQL> create table test (char_col varchar2(20));
Table created.
SQL> insert into test (char_col) values ('123456');
1 row created.
SQL>
SQL> select char_col,
2 replace(to_char(to_number(char_col), '99,99,99'), ',', '/') form_c
3 from test;
CHAR_COL FORM_C
-------------------- ---------
123456 12/34/56
SQL>
In other words:
- first convert character into a number (TO_NUMBER)
- apply valid format mask (TO_CHAR)
- replace comma with a slash (REPLACE)