title: How do I get running total for distinct values in a column
body: <p>I'd like to group by date range as the below example</p>
  
  <pre><code>    Date        ItemNo  Qty
  ==================================
  1/1/2014         101    20
  2/1/2014         102    10
  3/1/2014         103    5
  4/1/2014         104    10
  1/1/2014         101    5
  2/1/2014         101    10
  3/1/2014         102    15
  4/1/2014         104    20
  </code></pre>
  
  <p>I want to get the balance daily by sum the qty till that day grouped by ItemNo to be as below</p>
  
  <pre><code>Date        ItemNo  Qty
  ==================================
  1/1/2014      101   25
  2/1/2014      101   35
  2/1/2014      102   10
  3/1/2014      102   25
  3/1/2014      103   5
  4/1/2014      104   30
  </code></pre>
  
  <p>I know I can solve the problem by using cursors but I need another solution</p>
  
  <p>thanks</p>