Aggregate (SUM) by spark-sql

I am facing an issue while running aggregate of the order item subtotal by running in HiveContext. I am getting the result in below query

totalrevenue = sqlcontext.sql(“select sum(float(order_item_subtotal)) from order_items”)
But i am not able to verify the result of totalrevenue . when i try to print it gives me

print(totalrevenue)
DataFrame[_c0: double]

Can anyone please advise how to verify the result and is this enough to be able to get the answer in certification or we need to perform any other step?

Thanks
Plaban

try

totalrevenue.show()