如何检查表格中输入的数量是否大于数据库中的库存数量

Question

试图检查用户在表单上输入的数量是否大于库存。如果是，那么它应该在表单上将数量设置为 STOCK VALUE。

if (isset($_SESSION["cart_array"]))
{ 
    if (isset($_POST['item_to_adjust']) && $_POST['item_to_adjust'] != "") {
    // execute some code
    $item_to_adjust = $_POST['item_to_adjust'];
    $quantity = $_POST['quantity'];
    $quantity = preg_replace('#[^0-9]#i', '', $quantity); // filter everything   but       numbers
    if ($quantity >= 100) { $quantity = 99; }
    if ($quantity < 1) { $quantity = 1; }
    if ($quantity == "") { $quantity = 1; }

    $sqlquan = mysql_query("SELECT * FROM products WHERE id='$item_id' LIMIT 1");
        while ($row = mysql_fetch_array($sqlquan)) {
            $item_id= $row["id"];
            $stock= $row["stock"];
        }
            if ($quantity > $stock)
        {echo "much";
        $quantity=$stock;}

    $i = 0;
        foreach ($_SESSION["cart_array"] as $each_item) { 
              $i++;
              while (list($key, $value) = each($each_item)) {
                  if ($key == "item_id" && $value == $item_to_adjust) {
                      // That item is in cart already so let's adjust  its quantity using array_splice()
                      array_splice($_SESSION["cart_array"], $i-1, 1, array(array("item_id" => $item_to_adjust, "quantity" => $quantity)));
                  } // close if condition
              } // close while loop
    } // close foreach loop
}
}

问题是我的购物车中有 2 件商品。第一个的库存值为 15，第二个的库存值为 23。如果我为第一个产品输入的数量大于 15，则效果很好（将数量设置为 15）。但是，如果我为第二个产品输入一个大于 15 但小于 23 的值，它会与第一个产品的库存值进行比较并再次重置为 15。

Answer 1

相当多地清理了您的代码。希望这行得通。

if(isset($_SESSION["cart_array"])) {
    if(isset($_POST['item_to_adjust']) && !empty($_POST['item_to_adjust'])) {
        $item_to_adjust = $_POST['item_to_adjust'];
        $quantity = preg_replace('#[^0-9]#i', '', $_POST['quantity']); // filter everything but numbers
        if ($quantity >= 100) $quantity = 99;
        if (empty($quantity) || $quantity < 1) $quantity = 1;

        $sqlquan = mysql_query("SELECT * FROM products WHERE id='$item_to_adjust' LIMIT 1"); // You previously used id='$item_id', I think you meant $item_to_adjust

        // Since you have limited your query to only have 1 result, there is no need to use a while loop
        // also note in your original code the while loop was closed prematurely.
        $row = mysql_fetch_array($sqlquan);
        // No need to create new variables when $row is accessible directly

        if($quantity > $row["stock"]) {
            echo "Requested Quantity exceeds currently available Stock.<br>";
            $quantity = $row["stock"];
            echo "Quantity set to maximum available stock of ".$row["stock"]."<br>";
        }

        foreach($_SESSION["cart_array"] as &$each_item) {   // Referenced variable &$each_item so you do not have to use complicated array functions
            if($each_item['item_id'] == $item_to_adjust) {
                $each_item['quantity'] = $quantity;
                break; // Terminates the foreach loop
            }
        } // close foreach loop
    } else {
        echo("Invalid Item ID");
    }
}