use List::Util qw( max );

my %table;
my $max_size = 0;
for (
   # SELECT qty, size, price
   [ 100, 1, 43 ],
   [ 250, 1, 52 ],
   [ 100, 2, 45 ],
   [ 250, 2, 55 ],
   [ 100, 3, 50 ],
   [ 250, 3, 56 ],
   [ 200, 4, 55 ],
   [ 250, 5, 61 ],
) {
   my ($qty, $size, $price) = @$_;
   $table{$qty}[$size] = $price;
   $max_size = $size if $size > $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");
}

for my $qty (sort { $a <=> $b } keys(%table)) {
   print("<tr>");
   print("<th>$qty");
   for my $size (1..$num_cols) {
      print("<td>", defined($table{$qty}[$size]) ? "\$$table{$qty}[$size]" : '');
   }
}

print("</table>");