I'm starting to learn SQL and I'm working on this exercise: I have a "books" table which holds the info on every book (including price and genre ID). I need to get the name of the genre which has the highest average price. I suppose that I first need to group the prices by genre and then retrieve the name of the highest..

I know that I can get the results GENRE VS COST with the following:

select b.genre, 
       round(avg(b.price),2) as cost 
from books b 
group by b.genre;

My question is, to get the genre with the highest AVG price from that result, do I have to make:

select aux.genre 
from (
   select b.genre, 
          round(avg(b.price),2) as cost 
   from books b 
   group by b.genre
) aux 
where aux.cost = (select max(aux.cost) 
                  from (
                      select b.genre, 
                             round(avg(b.price),2) as cost 
                      from books l 
                      group by b.genre
                  ) aux);

Is it bad practice or isn't there another way? I get the correct result but I'm not confortable with creating two times the same selection.

I'm not using PL SQL so I can't use variables or anything like that..

Any help will be appreciated. Thanks in advance!