无法通过第47行的参考传递参数2 [关闭]

Hi guy's I'm having trouble with the above error with the following code, I have tried fixing it myself with the help from existing threads found on this site, please help.

<?php
$product_name=$_POST['product_name'];
$unique_id=uniqid();
$product_price=$_POST['product_price'];
$product_colour=$_POST['product_colour'];
$product_description=$_POST['product_description'];
$product_care=$_POST['product_care'];
$size=$_POST['size'];

error_reporting(E_ALL);
ini_set('display_errors', '1');

if (!$product_name || !$unique_id || !$product_price || !$product_colour || !$product_description || !$product_care || !$size) {
echo "You have not entered all the required details.<br />"
."Please go back and try again.";
exit;
}

if (!get_magic_quotes_gpc()) {
$product_name = addslashes($product_name);
$unique_id = addslashes($unique_id);
$product_price = doubleval($product_price);
$product_colour = addslashes($product_colour);
$product_description = addslashes($product_description);
$product_care = addslashes($product_care);
$size = addslashes($size);
}

include "mysql.connect.php";

//Using Prepared Statements, they also protect against SQL injection-style attacks Addison Wesley (2008) PHP and Web Development 4th edn, p. 280
$query = "insert into products values(NULL, ?, ?, ?, ?, ?, ?, ?)";
if( ! $stmt = $db->prepare( $query ) ) {
  echo 'Error: ' . $db->error;
  return false; // throw exception, die(), exit, whatever...
} else {
  // the rest of your code
}
$stmt->bind_param("sssd", NULL, $product_name, $unique_id, $product_price, $product_colour, $product_description, $Sproduct_care, $size);
$stmt->execute();
echo $stmt->affected_rows.'Item inserted into database.';
$stmt->close();
?>

Here's the mySQL table:

$stmt->bind_param("sssd", NULL, $product_name,...);

You can not pass NULL just like that. All arguments must be variable names that can be referenced.

Other thing is mentioned by @Fred-ii- in the comments: number of types does not match number of passed arguments. As for NULL value in first column, you are already using it in your query, so no need to pass it as parameter. Other thing that may not work as you expect is slashes in database. You are using prepared statement, so this fragment above:

if (!get_magic_quotes_gpc()) {
$product_name = addslashes($product_name);
...
}

will mess up your data.