如何将产品插入购物车然后注册或登录

Question

I have product , orderdetails and customer tables
the orderdetails table have products_id (FK) customers_id(FK) Quantity and size when customer is logged in and add items the items are inserted in the orderdetails table I want to allow the customer to add items/products to cart even without login then they can either login or register
Do I need another table for that ?

Database
productTable (products_id(pk), products_name , price,Quantity ,size )
customerTable (customers_id(pk), cust_name, cust_email )
orderdetails (products_id(FK), customers_id(FK), price,Quantity,size )

     <?php
include'config.php'; 
  session_start();  

if(isset($_SESSION['product_name']) && !empty($_SESSION['product_name'])) {
 $products_name =$_SESSION['product_name'];
 }
if(isset($_SESSION['products_price']) && !empty($_SESSION['products_price'])) {
 $products_price =$_SESSION['products_price'];
}


 if(isset($_SESSION['Quantity']) && !empty($_SESSION['Quantity'])) {
  $Quantity = $_SESSION['Quantity'];

 } 
  if(isset($_SESSION['product_id']) && !empty($_SESSION['product_id'])) {
  $product_id =   $_SESSION['product_id'];
 }
   if(isset($_SESSION['customers_id']) && !empty($_SESSION['customers_id'])) {
         $customers_id =   $_SESSION['customers_id'];

   } 
    if(isset($_SESSION['size']) && !empty($_SESSION['size'])) {
       $size =   $_SESSION['size'];

   } 
 $query = "INSERT INTO orderdetails  (products_id,customers_id,price,Quantity ,size) VALUES ('$product_id','$customers_id','$products_price','$Quantity','$size')";
mysqli_query($conn,$query) ;
    mysqli_close($conn);




?>  

Answer 1

Not necessarily. If customers_id is not a foreign key or part of, you could simply generate a new customer_id for each user not logged in and use this one. As soon as the user then logs in, you'd update the table:

UPDATE orderdetails SET customers_id = <id of user logged in>
    WHERE customers_id = <previous temporary id>

If the session expires, you would delete any entries again (a shopping cart of a user not logged in cannot survive expired sessions, of course):

DELETE FROM orderdetails WHERE customers_id = <temporary id> 

If customers_id is a foreign key, you need to additionally create a temporary customer entry as soon as the first item is added to the shopping car. Then, when the session expires, delete this entry, too. And you need to delete the temporary entry, as soon as a registered user logs in, together with the update of customer_id in orderdetails.