How to get ID on a specific row in PHP and MySQL

Question

PHP is giving me error of

Notice: Undefined index: product_id in C:\xampp\htdocs\odieinventory\admin\add_sales.php on line 6

This is my query

<?php 
  if (isset($_POST['addCart'])) {
    $product_id = $_POST['product_id'];
    $qtyBuy = $_POST['qtyBuy'];

    $addQuery = "INSERT INTO sales (product_id, quantity) VALUES ($product_id, $qtyBuy)";
    $execQuery = mysqli_query($connection, $addQuery);
  }
?>

This is my table

<form action="add_sales.php" method="POST">
        <?php 

          $query = "SELECT * FROM products";
          $exec = mysqli_query($connection, $query);

          while ($row = mysqli_fetch_array($exec)) {
            $product_id = $row['product_id'];
            $product_name = $row['product_name'];
            $description = $row['description'];
            $product_quantity = $row['quantity'];
            $product_price = $row['sell_price'];

         ?>
            <tr>
                <td class="text-center"><?php echo $product_id; ?>
                  <input type="hidden" name="product_id" value="<?php echo $product_id; ?>">
                </td>
                <td><?php echo $product_name; ?></td>
                <td><?php echo $description; ?></td>
                <td><?php echo $product_price; ?></td>
                <td><?php echo $product_quantity; ?></td>

                <td><input type="number" min="1" max="999" name="qtyBuy"></td>
            </tr>
         <?php } ?>

        </tbody>
      </table>
      </div>
      <div class="form-group">

          <input type="submit" name="addCart" value="Add Items to Cart" class="btn btn-info pull-right">

      </div>
   </div>
</form>

My Order Page

I would also like to ask for advice on how to insert records on my cart. By clicking 'Add Items to Cart', I like to pass ONLY the items with values on the quantitiy input on the cart. How to achieve this with PHP?

If you inspect the hidden element, do you actually see an id in the value? — Hanlet Escaño, Aug 25 '16 at 07:17
Possible duplicate of [PHP: "Notice: Undefined variable" and "Notice: Undefined index"](http://stackoverflow.com/questions/4261133/php-notice-undefined-variable-and-notice-undefined-index) — Justinas, Aug 25 '16 at 07:18
For multiple rows, you will clobber the form data `product_id` with each iteration. It will only ever submit the last one — Phil, Aug 25 '16 at 07:19

score 1 · Answer 1 · answered Aug 25 '16 at 07:22

1

First of all, you should never put users input ($_POST) directly into the SQL to avoid SQL injection - use prepared statements with mysqli.

It would be easiest for you to add a separate form with product ID and quantity field and an "Add to cart" button for each product in the table.

answered Aug 25 '16 at 07:22

Šimon Rozsíval

35
5

I'll read the links you've given. What do you mean on a seperate form? Can you explain further? – Odie Aug 25 '16 at 11:50
Well you wold iterate over the rows and inside each `` you would have a `
` for each product. It is not a perfect solution, but a really simple one.
– Šimon Rozsíval Aug 27 '16 at 09:10

score 1 · Accepted Answer · edited Jun 20 '20 at 09:12

In your table file table.php , you have to:

1- open the table and tbody HTML tags

2- make your html attributes form name as array (you have more than one input with the same name), in your case you are only submiting the last product_id and the last qtyBuy input values.

table.php

<form action="add_sales.php" method="POST">
       <div><table><tbody>
        <?php

          $query = "SELECT * FROM products";
          $exec = mysqli_query($connection, $query);
          while ($row = mysqli_fetch_array($exec)) {
            $product_id = $row['product_id'];
            $product_name = $row['product_name'];
            $description = $row['description'];
            $product_quantity = $row['quantity'];
            $product_price = $row['sell_price'];

         ?>
            <tr>
                <td class="text-center"><?php echo $product_id; ?>
                  <input type="hidden" name="product_id[]" value="<?php echo $product_id; ?>">
                </td>
                <td><?php echo $product_name; ?></td>
                <td><?php echo $description; ?></td>
                <td><?php echo $product_price; ?></td>
                <td><?php echo $product_quantity; ?></td>

                <td><input type="number" min="1" max="999" name="qtyBuy[]"></td>
            </tr>
            <?php } ?>

        </tbody>
      </table>
      </div>
      <div class="form-group">

          <input type="submit" name="addCart" value="Add Items to Cart" class="btn btn-info pull-right">

      </div>
</form>

In your add_sales.php file, you have to loop the $_POST['qtyBuy'] variable and check if the given quantity of each product is > 0

add_sales.php

<?php
   if (isset($_POST['addCart']) && $_POST['addCart']=="Add Items to Cart") {
     foreach($_POST['qtyBuy'] as $index=>$value){
       if($value > 0){
           $addQuery = "INSERT INTO sales (product_id, quantity) VALUES (".$_POST['product_id'][$index].", ".$value.")";
           $execQuery = mysqli_query($connection, $addQuery);
        }  
     }
  }
?>

I can't upvote your post because I'm new here. I'm also new on PHP. Anyway, do you have any links where to learn foreach? I also saw tutorials on using sessions. Thank you. — Odie, Aug 25 '16 at 11:48
hi you'r welcome --you can take a look here :https://www.codingunit.com/php-tutorial-foreach-loop — Amani Ben Azzouz, Aug 25 '16 at 12:33

How to get ID on a specific row in PHP and MySQL

2 Answers2

table.php

add_sales.php