title: How to do sum of sum in mysql query
body: <pre><code>SELECT a.id AS supplier, sum( processed_weight ) AS total_qty
  FROM supplier_inward a
  INNER JOIN warehouseb ON a.id = b.supplier
  WHERE a.master_product_id = '38'
  GROUP BY b.supplier
  </code></pre>
  
  <p>output present</p>
  
  <pre><code>supplier    total_qty
  12046      475.00
  12482      99.00
  </code></pre>
  
  <p>output needed</p>
  
  <pre><code>total_qty
  574.00
  </code></pre>
  
  <p>here i need the sum(total_qty) in this query? how to achieve this</p>