title: SSRS using an expression to sum a set of rows in a table
body: <p>I am using SSRS Reports and need to add an expression in a table that sums values in a column based on a value in the dataset.
  I believe the <code>SUM</code> function would work but I can't figure out how to use the expression part of the function to limit the sums to a value in the dataset.
  The dataset, <code>PatientRevenue</code> has a column <code>FullCharges</code> that I want to sum when the value in the column in the dataset <code>GroupName</code> is <code>Private</code>.
  I don't want the group name to appear in the table so I just added a <code>Total</code> row and want to add expressions in the cells to sum the rows.
  The expression I have that does not work is:
  <code>=Sum(Fields!FullCharge.Value, [GroupName] = "Private")</code>
  How do I set the expression in the <code>SUM</code> function to only sum values with a <code>GroupName = Private</code>?</p>