Loop to create multiple button in html and php

So basically what I am trying to do is using a loop to display multiple image and create a corresponding button to each image. If I pressed on the corresponding button, it will store the image into another database.

The first part display quite well. However, the second part I can hardly figure out how to determine the corresponding button for each image.

<?php while($row=mysqli_fetch_array($result)) { ?>
<div id="item">
  <?php echo '<img height="200" width="200" src="data:image;base64,'.$row[2]. '">';?>
  </br>
  <?php echo $row[ "name"];?>
  </br>
  <?php echo $row[ "price"];?>
  </br>
  <?php echo $row[ "description"];?>
  </br>
 <form>Quantity:
  <input type="text" value="" name="quantity" />
  </br>
  <input type="submit" value="add to cart" name="cart" />
 </form>
  <?php 
if (isset($_POST[ "cart"])){ 
$addtoname=$_SESSION[ 'username']; 
$addtoprice=$row[ 'price']; 
$addtodiscount=$row[ 'discount']; 
$addtoid=$row[ 'id']; 
$addtoimage=$row[ 'image']; 
$addtoquantity=$_POST[ 'quantity']; 
$hostname="localhost" ; 
$username="root";
$password="" ; 
$database="myproject" ; $con=mysqli_connect($hostname,$username,$password,$database) or die(mysqli_error()); 
$select=mysqli_select_db($con, "myproject")or die( "cannnot select db"); mysqli_query($con,"INSERT INTO cart(username,quantity,price,image,id,discount) VALUES('$addtoname','$addtoquantity','$addtoprice','$addtoimage','$addtoid','$addtodiscount')"); 
echo "success"; 
} 
else{ 
echo "fail"; 
}?>
</div>
<?php }//end of while ?>

It seems like it always go to fail AND never run into isset($_POST[ "cart"]))

Any tips will be much appreciated.

Thank you