title: Subtracting previous row minus current row in SQL
body: <p>I have a table <code>orders</code>.</p>
  
  <p>How do I subtract previous row minus current row for the column <code>Incoming</code>?</p>
  
  <p><img src="https://i.stack.imgur.com/ezndQ.jpg" alt="enter image description here"></p>