title: Difference between ISNULL(SUM(x),0) OR SUM(ISNULL(x,0) in SQL server
body: <p>Which one of the following is correct?</p>
  
  <pre><code>        SUM(ISNULL(Sales,0)) AS Sales,
          ISNULL(SUM(Sales),0) AS Sales,
  </code></pre>
  
  <p>Or are they both correct?</p>