Using a collection to sort a string

This a small function that allows to sort the content of a string (ASCII sort).
It use a collection or records to do the job:

CREATE OR REPLACE FUNCTION sort_string(pc$string IN VARCHAR2)
RETURN VARCHAR2
IS
  TYPE typ_rec IS RECORD(lettre VARCHAR2(10), nbre pls_integer);
  TYPE tab_rec IS TABLE OF typ_rec INDEX BY binary_integer;
  tabr tab_rec;
  LC$Result VARCHAR2(32767);
BEGIN

  FOR i IN 1 .. LENGTH(pc$string)
  LOOP
    tabr(ASCII(SUBSTR(pc$string, i, 1))).lettre := SUBSTR(pc$string, i, 1);
    tabr(ASCII(SUBSTR(pc$string, i, 1))).nbre   := NVL(tabr(ASCII(SUBSTR(pc$string, i, 1))).nbre, 0) + 1;
  END LOOP;

  FOR i IN tabr.FIRST .. tabr.LAST
  LOOP

    IF tabr.EXISTS(i) THEN
      LC$Result := LC$Result || rpad(tabr(i).lettre, tabr(i).nbre, tabr(i).lettre);
    END IF;

  END LOOP;

  RETURN LC$Result;
END;

That you can call with the following:

SQL> Begin
  2    dbms_output.put_line(sort_string('Zas95f1g6Az7b3k5a'));
  3  End ;
  4  /
1355679AZaabfgksz

PL/SQL procedure successfully completed.

Here are some links about 2 great articles about Sorting Collection from the AMIS Technology Blog:

Sorting PL/SQL Collections, the hard way, the intermediate way and the quite simple way (part one)
Sorting PL/SQL Collections, the quite simple way (part two: Have the SQL Engine do the heavy lifting)