You'll have to update that first line to refer to your MySQLi recordset: $getResults->TotalRows
You will have more lines to update too. You have to update the while loop.. to use: while (!$getResults->atEnd()) {
and
$row_getResults = mysqli_fetch_assoc($getResults);
would be:
$getResults->moveNext();
any reference to $row_getResults will have to be updated like: $getResults->getColumnVal("SizeID")