My basic Perl skills notwithstanding, glad I could help. With a bit more help from fuzzyping with this node here's a way to use H::T's LOOP feature to solve it another way (though I have used your concatenating method many times). The Perl:

#!/usr/bin/perl -w

print "Content-type: text/html\n\n";

use HTML::Template;
use strict;

my @datalist;
my $template = HTML::Template -> new(filename => "../htmlfilename.tmpl
+");

while (my @ary = $sth->fetchrow_array()) {
   my %one_record = ( 
      dataid => $ary[0],
      datalisting => $ary[1],
   );
   push (@datalist, \%one_record);
}

$template->param(datalist => \@datalist);
print $template->output();
[download]

And the HTML snippet:

<select name="xxxxx" size="4">
   <tmpl_if datalist>
      <tmpl_loop name="datalist">
         <option value="<tmpl_var name='dataid'>"><tmpl_var name='data
+listing'></option>
      </tmpl_loop>
   </tmpl_if>
</select>
[download]

Caveat: I did not test it with a database, but using trial data in the script it worked fine. And thanks for a good question, I learned something in the process of answering it! What PM's is all about. Good luck.