如何从php动作更新数据库的数量

时间：2017-12-14 09:34:57

标签： javascript php mysql database

我正在构建一个不同设备的数据库，该数据库显示在销售医疗设备的页面中。当用户将一定数量的设备添加到购物车时，我希望更新数据库（库存 - 数量在购物车中）我试图在PHP上执行此操作，但我没有运气。我的尝试和代码如下。

以下是我尝试的片段。我不知道在下面的代码中将它放在哪里。

<?php
    $value = isset($_POST['item']) ? $_POST['item'] : 1; //to be displayed
    if(isset($_POST['incqty'])){
       $value += 1;
        $query = "UPDATE products SET stock= (stock-$product_qty) WHERE product_name=$product_name";

        mysql_select_db('products');
        $retval = mysql_query($query,$mysqli);
    }

    ?>

这是index.php的代码

<?php
session_start();
include_once("config.php");

//current URL of the Page. cart_update.php redirects back to this URL
$current_url = urlencode($url="http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);
?>

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Shopping Cart</title>
<link href="style/style.css" rel="stylesheet" type="text/css">
</head>
<body>

<h1 align="center">Products </h1>

<!-- View Cart Box Start -->
<?php
if(isset($_SESSION["cart_products"]) && count($_SESSION["cart_products"])>0)
{
    echo '<div class="cart-view-table-front" id="view-cart">';
    echo '<h3>Your Shopping Cart</h3>';
    echo '<form method="post" action="cart_update.php">';
    echo '<table width="100%"  cellpadding="6" cellspacing="0">';
    echo '<tbody>';

    $total =0;
    $b = 0;
    foreach ($_SESSION["cart_products"] as $cart_itm)
    {
        $product_name = $cart_itm["product_name"];
        $product_qty = $cart_itm["product_qty"];
        $product_price = $cart_itm["product_price"];
        $product_code = $cart_itm["product_code"];
        $product_color = $cart_itm["product_color"];
        $bg_color = ($b++%2==1) ? 'odd' : 'even'; //zebra stripe
        echo '<tr class="'.$bg_color.'">';
        echo '<td>Qty <input type="text" size="2" maxlength="2" name="product_qty['.$product_code.']" value="'.$product_qty.'" /></td>';
        echo '<td>'.$product_name.'</td>';
        echo '<td><input type="checkbox" name="remove_code[]" value="'.$product_code.'" /> Remove</td>';
        echo '</tr>';
        $subtotal = ($product_price * $product_qty);
        $total = ($total + $subtotal);
    }
    echo '<td colspan="4">';
    echo '<button type="submit">Update</button><a href="view_cart.php" class="button">Checkout</a>';
    echo '</td>';
    echo '</tbody>';
    echo '</table>';

    $current_url = urlencode($url="http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);
    echo '<input type="hidden" name="return_url" value="'.$current_url.'" />';
    echo '</form>';
    echo '</div>';

}
?>
<!-- View Cart Box End -->

<!-- Products List Start -->


<?php
$results = $mysqli->query("SELECT product_code, product_name, product_desc, product_img_name, price, stock FROM products ORDER BY id ASC");
if($results){ 
$products_item = '<ul class="products">';
//fetch results set as object and output HTML
while($obj = $results->fetch_object())
{
$products_item .= <<<EOT
    <li class="product">
    <form method="post" action="cart_update.php">
    <div class="product-content"><h3>{$obj->product_name}</h3>
    <div class="product-thumb"><img src="images/{$obj->product_img_name}"></div>
    <div class="product-desc">{$obj->product_desc}</div>
    <div class="product-info">
    Price {$currency}{$obj->price} 

    <fieldset>

    <label>
        <span>Color</span>
        <select name="product_color">
        <option value="Black">Black</option>
        <option value="Silver">Silver</option>
        </select>
    </label>

    <label>
        <span>Quantity</span>
        <input type="text" size="2" maxlength="2" name="product_qty" value="1" />
    </label>

    </fieldset>
    <input type="hidden" name="product_code" value="{$obj->product_code}" />


    <input type="hidden" name="type" value="add" />
    <input type="hidden" name="return_url" value="{$current_url}" />





    <div align="center"><button type="submit" id="updateb" class="add_to_cart">Add</button></div>





    </div></div>
    </form>
    </li>
EOT;
}
$products_item .= '</ul>';
echo $products_item;
}
?>    
<!-- Products List End -->
</body>
</html>

这是cart_update.php的代码

<?php
session_start();
include_once("config.php");

//add product to session or create new one
if(isset($_POST["type"]) && $_POST["type"]=='add' && $_POST["product_qty"]>0)
{
    foreach($_POST as $key => $value){ //add all post vars to new_product array
        $new_product[$key] = filter_var($value, FILTER_SANITIZE_STRING);
    }
    //remove unecessary vars
    unset($new_product['type']);
    unset($new_product['return_url']); 

    //we need to get product name and price from database.
    $statement = $mysqli->prepare("SELECT product_name, price, stock FROM products WHERE product_code=? LIMIT 1");
    $statement->bind_param('s', $new_product['product_code']);
    $statement->execute();
    $statement->bind_result($product_name, $price, $stock);

    while($statement->fetch()){

        //fetch product name, price from db and add to new_product array
        $new_product["product_name"] = $product_name; 
        $new_product["product_price"] = $price;
        $new_product["product_stock"] = $stock;

        if(isset($_SESSION["cart_products"])){  //if session var already exist
            if(isset($_SESSION["cart_products"][$new_product['product_code']])) //check item exist in products array
            {
                unset($_SESSION["cart_products"][$new_product['product_code']]); //unset old array item
            }           
        }
        $_SESSION["cart_products"][$new_product['product_code']] = $new_product; //update or create product session with new item  
    } 
}


//update or remove items 
if(isset($_POST["product_qty"]) || isset($_POST["remove_code"]))
{
    //update item quantity in product session
    if(isset($_POST["product_qty"]) && is_array($_POST["product_qty"])){



        foreach($_POST["product_qty"] as $key => $value){
            if(is_numeric($value)){

                $_SESSION["cart_products"][$key]["product_qty"] = $value; //change
            }
        }
    }
    //remove an item from product session
    if(isset($_POST["remove_code"]) && is_array($_POST["remove_code"])){
        foreach($_POST["remove_code"] as $key){
            unset($_SESSION["cart_products"][$key]);
        }   
    }
}

//back to return url
$return_url = (isset($_POST["return_url"]))?urldecode($_POST["return_url"]):''; //return url
header('Location:'.$return_url);

?>

这是view_cart.php的代码

<?php
session_start();
include_once("config.php");
?>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>View shopping cart</title>
<link href="style/style.css" rel="stylesheet" type="text/css"></head>
<body>
<h1 align="center">View Cart</h1>
<div class="cart-view-table-back">
<form method="post" action="cart_update.php">
<table width="100%"  cellpadding="6" cellspacing="0"><thead><tr><th>Quantity</th><th>Name</th><th>Price</th><th>Total</th><th>Remove</th></tr></thead>
  <tbody>
    <?php
    if(isset($_SESSION["cart_products"])) //check session var
    {
        $total = 0; //set initial total value
        $b = 0; //var for zebra stripe table 
        foreach ($_SESSION["cart_products"] as $cart_itm)
        {
            //set variables to use in content below
            $product_name = $cart_itm["product_name"];
            $product_qty = $cart_itm["product_qty"];
            $product_price = $cart_itm["product_price"];
            $product_code = $cart_itm["product_code"];
            $product_color = $cart_itm["product_color"];
            $subtotal = ($product_price * $product_qty); //calculate Price x Qty

            $bg_color = ($b++%2==1) ? 'odd' : 'even'; //class for zebra stripe 
            echo '<tr class="'.$bg_color.'">';
            echo '<td><input type="text" size="2" maxlength="2" name="product_qty['.$product_code.']" value="'.$product_qty.'" /></td>';
            echo '<td>'.$product_name.'</td>';
            echo '<td>'.$currency.$product_price.'</td>';
            echo '<td>'.$currency.$subtotal.'</td>';
            echo '<td><input type="checkbox" name="remove_code[]" value="'.$product_code.'" /></td>';
            echo '</tr>';
            $total = ($total + $subtotal); //add subtotal to total var
        }

        $grand_total = $total + $shipping_cost; //grand total including shipping cost
        foreach($taxes as $key => $value){ //list and calculate all taxes in array
                $tax_amount     = round($total * ($value / 100));
                $tax_item[$key] = $tax_amount;
                $grand_total    = $grand_total + $tax_amount;  //add tax val to grand total
        }

        $list_tax       = '';
        foreach($tax_item as $key => $value){ //List all taxes
            $list_tax .= $key. ' : '. $currency. sprintf("%01.2f", $value).'<br />';
        }
        $shipping_cost = ($shipping_cost)?'Shipping Cost : '.$currency. sprintf("%01.2f", $shipping_cost).'<br />':'';
    }
    ?>
    <tr><td colspan="5"><span style="float:right;text-align: right;"><?php echo $shipping_cost. $list_tax; ?>Amount Payable : <?php echo sprintf("%01.2f", $grand_total);?></span></td></tr>
    <tr><td colspan="5"><a href="index.php" class="button">Add More Items</a><button type="submit">Update</button></td></tr>
  </tbody>
</table>
<input type="hidden" name="return_url" value="<?php 
$current_url = urlencode($url="http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);
echo $current_url; ?>" />
</form>
</div>

</body>
</html>

1 个答案:

答案 0 :(得分：0)

您的变量$product_qty和$product_name未定义，并且在查询中传递引号中的产品名称，因为您的查询是双引号，因此在单引号中传递名称。 如果使用主要ID而不是按名称更新，也会更好。

相关问题
最新问题