Extract all used symbols in column

Question

Hi all,
I've got varchar2 column where users can type all desired symbols. My need is to extract all used symbols (suppresing doubles).
select 'abcabcd123.,,,,%' from dual union all
select 'qqwwweabcabcd123.,,,,%' from dual My need is to extract "abcdeqw123.,%".
How do I perform it?

Answer 1

A list of used symbols could be extracted like this:
SQL> ed
Wrote file afiedt.buf
  1  with test as (
  2  select 'abcabcd123.,,,,%' txt from dual union all
  3  select 'qqwwweabcabcd123.,,,,%' txt from dual
  4  )
  5  --
  6  -- end of testdata
  7  --
  8  select
  9  character,
10  count(*)
11  from (
12     select
13     substr(test.txt,dummy.col,1) character
14     from test
15     join (
16        select level col
17        from dual
18        connect by level <= 40
19     ) dummy
20     on (
21        dummy.col <= length(test.txt)
22     )
23  )
24  group by character
25* order by character
SQL> /
C   COUNT(*)
%          2
,          8
.          2
1          2
2          2
3          2
a          4
b          4
c          4
d          2
e          1
q          2
w          3
13 rows selected.Change *40* to the maximum length of your column.
Will this suffice to get your list of used symbols? Or do you need it to be in one string?