[프로그래머스] SQL 고득점 kit JOIN 해답 모음

 

있었는데요 없었습니다 

https://school.programmers.co.kr/learn/courses/30/lessons/59043

datetime 은 비교연산자로 비교 가능하다

-- 코드를 입력하세요
SELECT ai.animal_id , ai.name

FROM ANIMAL_INS as ai join   ANIMAL_OUTS ao  on ai.animal_id = ao.animal_id

where ai.datetime > ao.datetime

order by ai.datetime asc;

 

 

오랜 기간 보호한 동물(1)

https://school.programmers.co.kr/learn/courses/30/lessons/59044

 

left join 으로 풀기 

SELECT ai.name AS NAME, ai.datetime AS DATETIME
FROM ANIMAL_INS AS ai
LEFT JOIN ANIMAL_OUTS AS ao ON ai.animal_id = ao.animal_id
WHERE ao.animal_id IS NULL
ORDER BY ai.datetime ASC
LIMIT 3;

 

서브 쿼리로 풀기 

SELECT NAME, DATETIME
FROM ANIMAL_INS
WHERE ANIMAL_ID NOT IN (
    SELECT ANIMAL_ID
    FROM ANIMAL_OUTS
)
ORDER BY DATETIME ASC
LIMIT 3;