title: How to sum columns in WQL?
body: <p>I want to calculate total and free disk space available on machine using WMI. and query for that is => select Size,FreeSpace from Win32_LogicalDisk.</p>
  
  <p>this query returns multiple rows as machine has more that one drive. If I sum this columns then I will get expected result. I can easily achieve this in sql by query</p>
  
  <p>SELECT sum(Size), sum(FreeSpace) FROM Win32_LogicalDisk</p>
  
  <p>but it gives error for wql.</p>
  
  <p>How can I achieve same in wql?</p>