Sweet alert in ajax and php content not working - php

Question

I'm trying to get a value from my database and then run an update using sweet alert pop-up but it is not working. The alert seem to pop-up and once the value is entered, it displays the value entered but not working. below is my actual ajax code:
viewproduct.php
<script>
$(document).ready(function() {
$('.btnupdatestock').click(function() {
var id = $(this).attr("id");
//var new_stock = $(this).val();
swal("Add Stock:", {
content: "input",
})
.then((updateStock) => {
$.ajax({
type: 'POST',
url: 'stock-in.php',
data:{
stock_up: updateStock,
},
success: function(data){
swal(`Updated: ${updateStock}`);
},
error: function(data){
swal(`Error updating: ${updateStock}`);
}
});
});
});
});
</script>
the above method was designed to trigger sql in stock-in.php and the code in stock-in.php is below:
<?php
include_once'connectdb.php';
if($_SESSION['useremail']=="" OR $_SESSION['role']=="Admin"){
header('location:index.php');
}
$idd=$_GET['id'];
$select=$pdo->prepare("select * from tbl_product where pid=$idd");
$select->execute();
while($row=$select->fetch(PDO::FETCH_OBJ)){
$productName = $row['pname'];
$oldstock = $row['pstock'];
//$id=$_POST['uid'];
$stockup=$_POST['stock_up'];
alert('I clicked');
$new_stock = $oldstock + $stockup;
$sql="UPDATE `tbl_product` SET `pstock` = ? WHERE pid= ? ";
$update=$pdo->prepare($sql);
$update->execute([$new_stock, $idd]);
if($result){
echo'Stock updated!';
}else{
echo'Error in updating stock';
}
}
?>
below is a picture of my UI that shows pop-up but it's not updating.
This is what I intend to do: If a user clicks on update and enters a value say 50, it should retrieve the old stock (database, say 100) and add to the new stock (value entered, say 50) and then update the database with 150. I am stuck here and any help would be appreciated. Thanks.

Answer 1

$(document).ready(function() {
$('.btnupdatestock').click(function() {
swal("Add Stock:", {
buttons: true,
closeModal: true,
content: "input",
}).then((updateStock) => {
if (updateStock === "") {
swal("You need to write something!");
return false
}else{
$.ajax({
type: 'POST',
url: 'stock-in.php',
data:{
stock_up: updateStock
<?php
echo ', id: '.$row->pid.' '
?>
<?php
echo ', oldstock: '.$row->pstock.' '
?>
},
success: function(data){swal(`Updated: ${updateStock}`);},
error: function(data){swal(`Error updating: ${updateStock}`);}
});
}
});
});
});
The major issue I had was I didn't make the SQL query global at the top of my page and then applied '.$row->pid.'