Species Revenue Leaderboard :Compare Species by Total Revenue to Identify Top-Earning Groups Intermediate

          with speciesrevenue as
  (select c.species,
          sum(o.totalamount) as totalrevenue
   from customers c
   join orders o on o.customerid = c.customerid
   group by c.species),
     roundedrevenue as
  (select species,
          totalrevenue,
          round(totalrevenue::numeric, -4) as roundedrevenue
   from speciesrevenue)
select species,
       totalrevenue,
       roundedrevenue,
       dense_rank() over (
                          order by roundedrevenue desc) as rank
from roundedrevenue;