title: SSRS how to subtract previous column value from column value in a group?
body: <p>The data it is passed to my SSRS report contains total shift output value. it is separated by hour, But to show actual hour output I have to subtract from previous column value:</p>
  
  <p>Current situation:</p>
  
  <pre><code>          07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 ...
  Line 1     25    55    79    105   130   155   185   205   ...
  </code></pre>
  
  <p>Expectation:</p>
  
  <pre><code>          07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 ...
  Line 1     25    30    24    26    25    25    30    30   ...
  </code></pre>
  
  <p>In the column value for the Group Hour I have:</p>
  
  <pre><code>=Fields!HourTotal.Value 
  </code></pre>