مشکل در وارد کردن مقادیر به جدول

سلام خسته نباشید من این کد رو نوشتم ولی قسمت result$ مشکل داره و اجرا نمیشه، خواهش میکنم کمک کنید خیلی ضروریه

نقل قول:

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<?php session_start();
$dbservername = "localhost";
$dbusername = "root";
$dbpassword = "";
$dbname = "library";

$con = mysqli_connect($dbservername, $dbusername, $dbpassword, $dbname) or die ;

$user = $_SESSION['username'];

if (isset($_SESSION['username']) && !empty($_SESSION['username'])){

$table = "CREATE TABLE IF NOT EXISTS ".$user." (
ID INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
user VARCHAR(30) NOT NULL,
uid INT(6) NOT NULL,
book VARCHAR(30) NOT NULL,
bid INT(6) NOT NULL,
writer VARCHAR(30) NOT NULL,
price INT(6) NOT NULL,
mail VARCHAR(30) NOT NULL,
buy_date TIMESTAMP
) ENGINE=InnoDB ";

if ($con->query($table) == FALSE){
echo "Error creating table: " . $con->error;
}}
else{
echo "login error!";
}
$ID = $_POST['ID'];

$bok = "SELECT * FROM books where ID = '$ID' ";
$resultb = $con->query($bok);
$rowb = $resultb->fetch_assoc();

$userr = "SELECT * FROM register where reguser = '$user' ";
$resultu = $con->query($userr);
$rowu = $resultu->fetch_assoc();

$bid = $rowb['ID'];
$book = $rowb['book'];
$price = $rowb['price'];
$writer = $rowb['writer'];
$uid = $rowu['ID'];
$mail = $rowu['regmail'];


if (!$con->set_charset("utf8"))
printf("Error loading character set utf8: %s\n", $mysqli->error);

$sql = "INSERT INTO admin (bid,book,price,writer,uid,mail) VALUES ('$bid','$book','$price','$writer','$uid','$mail') ";
$result = $con->query($sql);

if (!$result){
echo "error: ".mysqli_error($sql);
}else{
echo "done!";
}

?>

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