[프로그래머스] JOIN문

1. 없어진 기록 찾기

SELECT B.ANIMAL_ID, B.NAME
FROM ANIMAL_INS AS A
RIGHT JOIN ANIMAL_OUTS AS B
ON A.ANIMAL_ID = B.ANIMAL_ID
WHERE A.ANIMAL_ID IS NULL
ORDER BY B.ANIMAL_ID

 

2. 있었는데요 없었습니다.

SELECT A.ANIMAL_ID, A.NAME
FROM ANIMAL_INS AS A
INNER JOIN ANIMAL_OUTS AS B
ON A.ANIMAL_ID = B.ANIMAL_ID
WHERE A.DATETIME > B.DATETIME
ORDER BY A.DATETIME

 

3. 오랜 기간 보호한 동물(1)

SELECT A.NAME, A.DATETIME
FROM ANIMAL_INS AS A
LEFT JOIN ANIMAL_OUTS AS B
ON A.ANIMAL_ID = B.ANIMAL_ID
WHERE B.ANIMAL_ID IS NULL
ORDER BY A.DATETIME
LIMIT 3

 

4. 보호소에서 중성화한 동물

SELECT A.ANIMAL_ID, A.ANIMAL_TYPE, A.NAME
FROM ANIMAL_INS AS A
INNER JOIN ANIMAL_OUTS AS B
ON A.ANIMAL_ID = B.ANIMAL_ID
WHERE A.SEX_UPON_INTAKE LIKE 'Intact%' AND B.SEX_UPON_OUTCOME NOT LIKE 'Intact%'
ORDER BY A.ANIMAL_ID