select 
  o.cust_code as CODE 
  ,c.cust_name as NAME 
  ,count(0) as CNT  --顧客ごとの受注件数
  ,sum(order_amnt) as TTL_AMT 
  ,round(avg(order_amnt), 1) as AVG_AMT 

from orders as o

inner join customer as c 
  on o.cust_code = c.cust_code 
where order_date >= '2023-09-01'
  and order_date <= '2023-09-30'
group by 1,2
having CNT >= 5 
order by CNT desc, AVG_AMT desc, CODE
limit 5
;