[PGS]없어진 기록 찾기

• NOT IN을 활용한 풀이

SELECT ANIMAL_ID, NAME
FROM ANIMAL_OUTS
WHERE ANIMAL_ID NOT IN (SELECT ANIMAL_ID FROM ANIMAL_INS);

• LEFT JOIN을 활용한 풀이

SELECT outs.animal_id, outs.name
FROM animal_outs AS outs
	LEFT JOIN animal_ins AS ins
	ON outs.animal_id = ins.animal_id
WHERE ins.animal_id IS NULL;