GROUP BY

https://programmers.co.kr/learn/courses/30/parts/17044

고양이와 개는 몇 마리 있을까

SELECT ANIMAL_TYPE, COUNT (*) AS count
FROM ANIMAL_INS
GROUP BY ANIMAL_TYPE
ORDER BY ANIMAL_TYPE

동명 동물 수 찾기

SELECT NAME, COUNT(NAME)
FROM ANIMAL_INS
WHERE NAME != 'NULL'
GROUP BY NAME
HAVING COUNT(NAME) >= 2
ORDER BY NAME

입양 시각 구하기 (1)

SELECT HOUR(DATETIME) AS HOUR, COUNT(DATETIME) AS COUNT
FROM ANIMAL_OUTS
WHERE HOUR(DATETIME) >= 9 AND HOUR(DATETIME) <= 19
GROUP BY HOUR
ORDER BY HOUR