Lets say we have employees table and we want sum on salary column.
Drag viewobject and create table normally.
Select Salary table -> Right Click -> Facet Column -> Footer
From structure pane for this column add output text filed and surround it with panel grouplayout (layout property as horizontal and halign as right)
You can have two view object viz one for just employees and secont view object to contain the sum query.
The output text should refer to the sum value of the second view.
Checout the attached application
https://docs.google.com/open?id=0B-zSRgGSIJgNMTIyMTk1Y2ItMDNjMS00N2Y5LWFkYWItNWI4YWY4YzUyZWQ2
