월별 잡은 물고기 수 구하기

문제

https://school.programmers.co.kr/learn/courses/30/lessons/298519

프로그래머스

 

 

FISH_INFO
ID	FISH_TYPE	LENGTH	TIME
0	0	30	2021-12-04
1	0	50	2020-03-07
2	0	40	2020-03-07
3	1	20	2022-03-09
4	1	null	2022-04-08
5	2	13	2021-04-28
6	3	60	2021-07-27
7	0	55	2021-01-18
8	2	73	2020-01-28
9	3	73	2021-04-08
10	2	22	2020-06-28
11	2	17	2022-12-23

 

 

풀이

select 
    count(*) as FISH_COUNT
    ,max(LENGTH) as MAX_LENGTH
    ,FISH_TYPE as FISH_TYPE

from 
    FISH_INFO
    
group by FISH_TYPE
having avg(ifnull(LENGTH,10)) >= 33

order by FISH_TYPE

10이하는 null이라고 했으니 ifnull로 10 취급해준다 

 

그럼 이떄 null이 아니면 어떻게 해야할까??!

        CASE
            WHEN LENGTH <= 10 THEN 10
            ELSE LENGTH
        END

 

조건문을 써서 바꿔주면 됩니다