(프로그래머스 SQL 문제 풀이) 이름이 없는/있는 동물의 아이디, NULL 처리하기

SELECT ANIMAL_ID FROM ANIMAL_INS
WHERE NAME IS NULL
ORDER BY ANIMAL_ID 

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SELECT ANIMAL_ID FROM ANIMAL_INS
WHERE NAME IS NOT NULL
ORDER BY ANIMAL_ID

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SELECT ANIMAL_TYPE, IFNULL(NAME, 'No name'), SEX_UPON_INTAKE 
FROM ANIMAL_INS
ORDER BY ANIMAL_ID