如何用php中的金额更新购物车数量？

Question

Below is my not working source code? I want to update the quantity with respective to that perticular item and calculating total. I was stuck or did wrong coding. Please can anyone tell me what to do furture ? means when user increasing quantity price of that item should be incremented..

         $sel_user = "select * from cart where ip_add = '$ip' ";

            $run_sel_user = mysqli_query($con,$sel_user);

            while($p_price = mysqli_fetch_array($run_sel_user))
            {
                $pro_id = $p_price['p_id'];

                $sel_pro_from_product = "select * from products where product_id = '$pro_id'";

                $run_pro_from_product = mysqli_query($con,$sel_pro_from_product);

                while($pro_price = mysqli_fetch_array($run_pro_from_product))
                {

                    $product_price = array($pro_price['product_price']);

                    $product_title = $pro_price['product_title'];

                    $product_image = $pro_price['product_img1'];

                    $product_single_price = $pro_price['product_price'];

                    $values = array_sum($product_price);

                    $total += $values ;
                    if(isset($_POST['update_cart']))
                    {
                        if(isset($_POST['qty']))
                        {
                            print_r($_POST['qty']);
                            foreach($_POST['qty'] as $qty_add)
                            {

                                $qty = $qty_add;
                                $update_qty = "update cart set qty='$qty' where p_id='$pro_id'";
                                $run_qty = mysqli_query($con,$update_qty);
                                $total=$total*$qty;
                            }
                        }
                        else
                        {

                        }
                    }

            ?>
            <tr align="center" >
                <td style="padding:5px; border:1px solid black;"><input type="checkbox" name="remove[]" value="<?php echo $pro_id;?>"/></td>

                <td style="padding:5px; border:1px solid black;"><?php echo $product_title;?><br>
                    <img src="admin_area/product_images/<?php echo $product_image; ?>" height="60" width="60"/>
                </td>
                <td style="padding:5px; border:1px solid black;"><input type="text" size="4" name="qty[]" 
                    value="<?php
                            $default_qty = 1;
                            if(!isset($_POST['qty']))
                            {
                                echo $default_qty;
                            }


                    ?>" style="text-align:center;"/></td>


                        <td style="padding:5px; border:1px solid black;"><?php echo $product_single_price." Rs ";?></td>
                    </tr>
                    <?php   
                }}

                    ?>

Answer 1

You are setting the name of your input box as a qty[] array, and both looping for each item in the cart and each item in the array So if you have 20 items in the cart, you are currently sending 20x20 queries, and 19 out of the 20 would contain the wrong info. Instead you can set the name of the input box using $pro_id variable.

<input type="text" size="4" name="qty<?php echo($pro_id);?>"/>

This way each of your textbox will have its own unique name, and that name identifies which product it is. Then in your while loop above you could do something like this

if(isset($_POST['update_cart']))
{
    if(isset($_POST['qty' . $pro_id]))
    {
        $quantity = (int)$_POST['qty' . $pro_id];
        $run_qty = mysqli_query($con,"update cart set qty='$qty' where p_id='$pro_id'");
    }
}

But of course, the way it's setup right now, there is no way to know which records in the cart table belongs to which users. So this would not work in the real world setup without more changes (like a field identifying which records belong to which user)