Add unique identifier to first iteration in PHP for loop

Question

I am using a for loop on my client's website to insert purchased ticket information into a database. The loop is working correctly, but the client has requested the option to attach a unique identifier to the first entry every time the for loop is run. This identifier would be used to highlight the primary ticket owner when the tickets are printed. I have included the current for loop below for reference. Any ideas on how to achieve this? Thank you.

$threepack = '';
$i = '';
for($i = 0; $i < $tickets; $i++)
{
    $firstname = 'firstname'.$threepack;
    $lastname = 'lastname'.$threepack;
    $address = 'address'.$threepack;
    $city = 'city'.$threepack;
    $postal = 'postal'.$threepack;
    $phone = 'phone'.$threepack;
    $altphone = 'altphone'.$threepack;
    $sec_firstname = 'sec_firstname'.$threepack;
    $sec_lastname = 'sec_lastname'.$threepack;
    $email = 'email'.$threepack;

    $table->firstname = $data->$firstname;
    $table->lastname = $data->$lastname;
    $table->address = $data->$address;
    $table->city = $data->$city;
    $table->postal = $data->$postal;
    $table->phone = $data->$phone;
    $table->altphone = $data->$altphone;
    $table->sec_firstname = $data->$sec_firstname;
    $table->sec_lastname = $data->$sec_lastname;
    $table->email = $data->$email;
    $table->id = 0;
    $table->order_total = $data->total;
    $table->store();

    if($data->tickets == '-1')
    {
        if($threepack == 2)
        {
            $threepack = 3;
        } else {
            $threepack = 2;
        }
    }

    // 8 Fields
    if($data->tickets == '5')
    {
        if ($threepack == '') {
            $threepack = 2;
        } else {
            $threepack += 1;
        }
    }
}

Answer 1

for ($i = 0; $i < $tickets; $i++) {
  // ...

  if ($i == 0)
    $table->highlightme = 1;
  // ...

  $table->store();

  // ...
}