$name = $_POST['nickname'];
 $coupons = $_POST['donate_opt'];
 $count = $_POST['count_coupons'];
 $lottery = $_POST['event'];
 $streamer = $_POST['streamer'];

$total_coupons = $coupons*$count;
 for($i = 0; $i < $total_coupons; $i++){
    $sql = 'INSERT INTO coupons(name, lottery_id, streamer_id) VALUES(?, ?, ?)';
    $up = $conn->prepare($sql);
    $up->bindParam(1, $name);
    $up->bindParam(2, $lottery);
    $up->bindParam(2, $streamer);
    $conn->beginTransaction();
    $up->execute();
    $conn->commit();
}