IS NULL 값이 없음을 의미 IFNULL( ~~, ' ') AS ~~ 값이 NULL인 경우 다르게 표시하고 싶을 때 사용 SELECT ANIMAL_ID FROM ANIMAL_INS WHERE NAME IS NULL ORDER BY ANIMAL_ID; SELECT ANIMAL_ID FROM ANIMAL_INS WHERE NAME IS NOT NULL ORDER BY ANIMAL_ID; SELECT ANIMAL_TYPE, IFNULL(NAME,'No name') AS NAME, SEX_UPON_INTAKE FROM ANIMAL_INS ORDER BY ANIMAL_ID;