...
tie %th, 'My::DB::User', {-where=>'active=1'};
for (my $i=0; $i < $th{'_ROWCOUNT_'}; $i++)
{   $th{'_CURRENTROW_'} = $i;
    print "$th{'username'} has been an active member since $th{'created'}\n";
}

##</code><code>##

...
while ($th{'_CURRENTROW_'} < $th{'_ROWCOUNT_'})
{   #do something, then:
    $th{'_CURRENTROW_'}++;
}