[프로그래머스/SQL 고득점 Kit/MySQL] IS NULL

https://school.programmers.co.kr/learn/challenges?tab=sql_practice_kit 

프로그래머스

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<IS NULL>
Q.경기도에 위치한 식품창고 목록 출력하기

SELECT
    WAREHOUSE_ID
    , WAREHOUSE_NAME
    , ADDRESS
    , IFNULL(FREEZER_YN,'N') as FREEZER_YN
FROM FOOD_WAREHOUSE 
WHERE ADDRESS LIKE '경기도%'
ORDER BY WAREHOUSE_ID

Q.이름이 없는 동물의 아이디

SELECT ANIMAL_ID
FROM ANIMAL_INS 
WHERE NAME IS NULL
ORDER BY ANIMAL_ID

Q.이름이 있는 동물의 아이디

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

Q.NULL 처리하기

SELECT 
    ANIMAL_TYPE
    , IFNULL(NAME,"No name") as NAME
    , SEX_UPON_INTAKE
FROM ANIMAL_INS

Q.나이 정보가 없는 회원 수 구하기

SELECT COUNT(*)
FROM USER_INFO 
WHERE AGE IS NULL