如何在php的会话变量中附加数据？

Question

我正在开发购物车应用程序。在此选定的产品 id 存储在会话变量中。如果用户想在购物车中添加其他产品，他将点击 Add More... 按钮。我想在同一会话变量中附加选定产品的 ID。

我的代码是：

shop_details_cart.php

$get_ids = $_GET['ids']; 
$ids =  json_decode($get_ids,true);
$id_string = implode(',', array_map(function ($entry) {
 return $entry['id'];
}, $ids));
//$_SESSION['ids'];
//array_push($_SESSION['ids'],$id_string);
$_SESSION['ids']=$id_string;
$sql=mysql_query("select product_id,name,stock from $shop_loc where product_id IN($_SESSION[ids])");

Answer 1

if(isset($_SESSION['ids'])){
    $_SESSION['ids'].=$id_string.",";
} else {
    $_SESSION['ids']=$id_string.",";
}


$sql=mysql_query("select product_id,name,stock from $shop_loc where product_id IN(".trim($_SESSION[ids],",").")");

Answer 2

https://stackoverflow.com/a/32155938/7439186改进

if(isset($_SESSION['ids'])){
        $_SESSION['ids'].= ' , '.$id_string;
    } else {
        $_SESSION['ids']=$id_string;
    }


    $sql=mysql_query("select product_id,name,stock from $shop_loc where product_id IN(".trim($_SESSION[ids],",").")");