Question : Sorting a varchar field numerically

We have apartment numbers stored in the database as a small varchar.  When I pull the apartments from a building and display them I'd like to show the apartments in numeric order as opposed to binary order that the order by returns in the query.  Unfortunately CAST and CONVERT don't handle strings such as "10A" when trying to convert to an integer, they just give an error.  I figured I could do a huge nested replace() call to pull out all characters except numbers but it seems like a huge waste and there must be an easier way.  Is it easier to just pull the data and then sort it using ASP?

To summarize:

Right now I'm getting this:
1A
1B
10A
10B
2A
3C

What I'd like is:
1A
1B
2A
3C
10A
10B

Thanks in advance!

Answer : Sorting a varchar field numerically

heres a generic solution for you.

create or replace function get_number (
 p_str_in   in  varchar2
)
  return number
  deterministic
is
 
  /* Variables */
  -- Components of match.
  t_component    sys.owa_text.vc_arr;
  -- Return string.
  v_ret          number := 0;
 
begin

  if (sys.owa_pattern.match(p_str_in, '([0-9.]*).*', t_component))
  then
    v_ret := t_component(1);
  end if;

  return v_ret;
 
end get_number;
/

now to test it out:
SQL> create table test (
  2    text  varchar2(30)
  3  )
  4  /

Table created.

SQL> insert into test values ('1A');

1 row created.

SQL> insert into test values ('22B');

1 row created.

SQL> insert into test values ('101Scribble');

1 row created.

SQL> insert into test values ('3temp');

1 row created.

SQL> insert into test values ('3.2test');

1 row created.

SQL> commit
  2  /

Commit complete.

SQL> REM This next index is a function based index..
SQL> REM get your dba to grant you QUERY REWRITE
SQL> REM or it will fail with ORA-01031: insufficient privileges
SQL> create index test_idx1 on test (get_number(text))
  2  
SQL> /

Index created.

SQL> select text
  2    from test
  3   order by get_number(text)
  4  /

TEXT
------------------------------
1A
3temp
3.2test
22B
101Scribble

SQL>