[SQL문제풀기] 연도 별 평균 미세먼지 농도 조회하기

문제

MYSQL

내가 작성한 오답

select year(ym) year, round(avg(PM_VAL1),2) PM10, round(avg(PM_VAL2),2) PM2.5
from air_pollution
where location2 = '수원'
group by 1
order by 1 asc

내가 작성한 정답

select year(ym) year, round(avg(PM_VAL1),2) 'PM10', round(avg(PM_VAL2),2) 'PM2.5'
from air_pollution
where location2 = '수원'
group by 1
order by 1 asc