Thanks - I tried revising it to the below and still got an error. We're eyeballs deep in an implementation and this was just an interview question I'd love to have an answer for, but for now I've got to table it until that golden day in the very distant future I've got time to play lol case when (SUM(case when {type} = 'Invoice' then {amount} when {type} = 'Sales Order' then (-1 * {amount}) else 0 end) > 0 then 'Great!' else 'Not Great!' end