my $max_size = 5;  # SELECT MAX(size)

print("<table>");
print("<tr>");
print("<th>");
print("<th>Sizes");

print("<tr>");
print("<th>QTY");
for my $size (1..$max_size) {
   print("<th>$size");
}

my $last_qty;
my $last_size;
for (
   # SELECT qty, size, price ORDER BY qty ASC, size ASC
   [ 100, 1, 43 ],
   [ 100, 2, 45 ],
   [ 100, 3, 50 ],
   [ 200, 4, 55 ],
   [ 250, 1, 52 ],
   [ 250, 2, 55 ],
   [ 250, 3, 56 ],
   [ 250, 5, 61 ],
) {
   my ($size, $qty, $price) = @$_;
   if (!defined($last_qty) || $qty != $last_qty) {
      if (defined($last_size)) {
         print("<td>") for $last_size+1 .. $max_size;
         $last_size = 0;
      }

      print("<tr>");
      print("<th>$qty");
      $last_qty = $qty;
   }

   print("<td>") for $last_size+1 .. $size-1;
   print("<td>\$$price");
}

if (defined($last_size)) {
   print("<td>") for $last_size+1 .. $max_size;
}

print("</table>");