title: MYSQL query minus operator not working
body: <p>Looked up of all questions about error with minus operator in MYSQL and can't find solution.
  all given solutions not working. 
  i`m trying to get difference between Units In Stock and Units On Order
  and my query like this:</p>
  
  <pre><code>$sql = "SELECT   UnitsInStock - UnitsOnOrder as 'Difference'
          FROM products ";
  </code></pre>
  
  <p>why i got this error?</p>
  
  <pre><code> Warning: mysqli_query(): (22003/1690): BIGINT UNSIGNED value is out of range
  </code></pre>