The Rare and the Profitable :Identify High-Revenue Products Among Low-Inventory Items Using Recent Sales Data Advanced

          with recentsales as
  (select p.productid,
          p.name as productname,
          i.quantityavailable,
          sum(od.quantity * p.price) as totalrevenue
   from orderdetails od
   join orders o on od.orderid = o.orderid
   join products p on od.productid = p.productid
   join inventory i on p.productid = i.productid
   where o.orderdate::timestamp >= current_date - interval '30 days'
   group by p.productid,
            p.name,
            i.quantityavailable)
select productid,
       productname,
       quantityavailable,
       totalrevenue,
       ntile(4) over (
                      order by totalrevenue desc) as demandtier
from recentsales;