RE: Re: select substr??? - Mailing list pgsql-sql

And if you have plperl installed, something like this is even easier:
create function texttrim(text) returns text as '$_[0] =~ s/\\W//g; return
$_[0]' language 'plperl';
(I just read the docs) :-)

> -----Original Message-----
> From:    Jeff Eckermann [SMTP:jeckermann@verio.net]
> Sent:    Tuesday, April 10, 2001 5:41 PM
> To:    pgsql-sql@postgresql.org
> Subject:    RE: Re: select substr???
> 
> Regular expressions make this much easier.  The below could be shortened
> to:
> 
>         create function ComparisonString(text) returns text  as '
>       declare
>         t alias for $1;
>         r text;
>         c char;
>     begin   
>         if t is null  or t !~ ''[^a-zA-Z0-9]''
>        then
>           return t;
>         end if;
>         r = '''';
>         for i in 1 .. char_length(t) loop
>           c = substring(t from i for 1);
>           if c ~ ''[a-zA-Z0-9]''
>           then
>               r = r || c;
>           end if;
>         end loop;
>         return r;
>       end;
>     ' language 'plpgsql' with (IsCachable);
> 
> 
> 
> > -----Original Message-----
> > From:    Albert REINER [SMTP:areiner@tph.tuwien.ac.at]
> > Sent:    Tuesday, April 10, 2001 11:38 AM
> > To:    pgsql-sql@postgresql.org
> > Subject:    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.
> > 
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> > 
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