4-3 실습에서 select

case when avg_price<5000 then avg_price*0.005

when avg_price<20000 then avg_price*0.01

when avg_price<30000 then avg_price*0.02

else avg_price*0.03 end "수수료"

from

(

select restaurant_name,avg(price/quantity) as avg_price

FROM food_orders

group by restaurant_name

) a
해당 코드 어디가 틀렸는지, 왜 이렇게하면 오류가뜨는지 모르겠습니다 ㅠㅠ