use strict;    # use em if
  use warnings;  #   you're not already

  my @loop;

  # first, prepare the SQL .. this can be more efficient.
  # BUT more importantly, this also is using placeholders
  # ALSO note the column aliases .. this makes things more convenient below.
  my $sth = $dbh->prepare("SELECT item1 as _first_item, item2 as _second_item, item3 as _third_item FROM table WHERE topic = ? ORDER BY id ASC");

  # no need for a $y index ..
  foreach my $topic ( @topic[0 .. $x-1] ){  # just use an array slice to get the topics
    $sth->execute( $topic );    # passing a value to the placeholder
    push @loop, {
      _TOPIC => $topic,
      _ITEMS => $sth->fetchall_arrayref({}),   # use a DBI function to get the AoH of items
    };
  }

  $html->param(_TOPICS => \@loop);
  $html->output;

##</code><code>##

  my $sth = $dbh->prepare("SELECT item1 as _first_item, item2 as _second_item, item3 as _third_item FROM table WHERE topic = ? ORDER BY id ASC");
  my @loop = map {
    $sth->execute( $_ );
    {  _TOPIC => $_,  _ITEMS => $sth->fetchall_arrayref({})  };
  } @topic[0 .. $x-1];