title: getting a warning on php website Warning: A non-numeric value encountered in C:\xampp\htdocs\InventoryMS\dashboard.php on line 15
body: <p>I downloaded a website from github and it's working fine except that it is showing warning in dashboard like this:
  <a href="https://i.stack.imgur.com/mJfGN.png" rel="nofollow noreferrer">dashboard</a></p>
  <p>I want to know how to solve this. Here's the code of dashboard and line 15:</p>
  <pre><code>&lt;?php require_once 'includes/header.php'; ?&gt;
  
  &lt;?php 
      
  $sql = &quot;SELECT * FROM product WHERE status = 1&quot;; 
  $query = $connect-&gt;query($sql); 
  $countProduct = $query-&gt;num_rows;
      
  $orderSql = &quot;SELECT * FROM orders WHERE order_status = 1&quot;;
  $orderQuery = $connect-&gt;query($orderSql); 
  $countOrder = $orderQuery-&gt;num_rows;
      
  $totalRevenue = &quot;&quot;; 
  while ($orderResult = $orderQuery-&gt;fetch_assoc()) {     
      $totalRevenue += $orderResult['paid'];   //line 15 
  }
      
  $lowStockSql = &quot;SELECT * FROM product WHERE quantity &lt;= 3 AND status = 1&quot;;
  $lowStockQuery = $connect-&gt;query($lowStockSql); 
  $countLowStock = $lowStockQuery-&gt;num_rows;
      
  $userwisesql = &quot;SELECT users.username , SUM(orders.grand_total) as
  totalorder FROM orders INNER JOIN users ON orders.user_id =
  users.user_id WHERE orders.order_status = 1 GROUP BY
  orders.user_id&quot;;
  $userwiseQuery = $connect-&gt;query($userwisesql);
  $userwieseOrder = $userwiseQuery-&gt;num_rows;
  
  $connect-&gt;close();
  
  ?&gt;
  </code></pre>
  <p>Here's the database table orders:
  <a href="https://i.stack.imgur.com/g2iF6.png" rel="nofollow noreferrer">database</a></p>