php - Data does not insert into table using checkbox - php

Question

the checkbox is not working.. I could not insert new data into the table
there is nothing happen when I click the "add to cart" button.
<div class="carousel-inner">
<div class="item">
<ul class="thumbnails">
<?php
$query = mysql_query("SELECT * FROM product where pro_category='3' LIMIT 0,4 ");
while ($data = mysql_fetch_assoc($query)):
?>
<li class="span3">
<div class="product-box">
<span class="sale_tag"></span>
<?php echo '<p><img src="admin/pro_image/'.$data['image'].'" /></p>'; ?>
<?php echo ''.$data['name_nl'].''; ?>
<br/>
<td><input class='minuman' type='checkbox' name='add[]' value='<?php echo '<a class="btn btn-success" href="cart.php?add='.$data['code'].'" class="category">
</a>'; ?>'></td>
<p class="price"><?php echo 'RM '.$data['price']; ?></p>
</div>
</li>
<?php endwhile; ?>
</ul>
</div>
</div>
<ul class="thumbnails" align="center">
<div id="single_product" align="center">
<?php echo '<a class="btn btn-success" href="cart.php?add='.$data['code'].'" class="category">Add to Cart</a>'; ?>
</div>
</ul>
this is my code for insert cart:
if(isset($_GET['add'])){
$id = $_GET['add'];
$qt = mysql_query("SELECT code, quantity FROM product WHERE code='$id'");
while($qt_row = mysql_fetch_assoc($qt)){
if($qt_row['quantity'] != $_SESSION['cart_'.$_GET['add']] && $qt_row['quantity'] > 0){
$_SESSION['cart_'.$_GET['add']]+='1';
header("Location: keranjang.php");
} else {
echo '<script language="javascript">alert("Stok produk tidak mencukupi!"); document.location="index.php";</script>';
}
}
}

Answer 1

According to PHP Documentation, mysql_query is deprecated since PHP 5.5.0, and removed in PHP 7.0.0. You may use mysqli or PDO instead.
This row might cause problems, because it's not escaped:
<td><input class='minuman' type='checkbox' name='add[]' value='<?php echo '<a class="btn btn-success" href="cart.php?add='.$data['code'].'" class="category">
</a>'; ?>'></td>
and this is one of the ways to escape:
<td>
<input class="minuman" type="checkbox" name="add[]" value="<?php echo '<a class="btn btn-success" href="cart.php?add=' . $data['code'] . '" class="category"></a>'; ?>" />
</td>
About "add to cart" - You can store the products in the session or in a cookie (I think cookies can be a better option), and then show them in the cart.