Re: Re: select substr???

On Mon, Apr 09, 2001 at 06:05:55PM +0100, Tim Johnson wrote:
> Hi,
> 
> I have postgres 6.x (where x is something).
> 
> I have the following list of data
> 
> data
> --------
> ABC*
> ABC
> ABC-
...
> what I want to do is 'select distinct(data) [ignoring non alphanumeric
> characters] order by data'

somewhere I use the following, which might be adapted to do what you
want.  I am sure there are more elegant ways of doing this, though.
    create function ComparisonString(text) returns text  as ' declare   t text;   r text;   c char;   ns bool; begin
if$1 is null then     return NULL;   end if;   t = lower(trim(both $1));   r = '''';   ns = false;   for i in 1 ..
char_length(t)loop     c = substring(t from i for 1);     if c = '' '' then       if ns then         r = r || '' '';
  end if;       ns = false;     else       if position(c in ''abcdefghijklmnopqrstuvwxyz0123456789'') > 0 then
r= r || c;         ns = true;       end if;     end if;   end loop;   return trim(both r); end;
 
' language 'plpgsql' with (IsCachable);

Albert.