[MySQL] 프로그래머스

꼭 SQL짱이 될거야..!
SQL 짱이 돼서 데이터 베이스 패고 다닐거야!

중복 없이 SELECT

SELECT DISTINCT Country FROM Customer;
SELECT COUNT(DISTINCT Country) FROM Customers;

칼럼 내의 이름 으로 구별해 COUNT

SELECT ANIMAL_TYPE, COUNT(ANIMAL_TYPE)
FROM ANIMAL_INS
GROUP BY ANIMAL_TYPE
ORDER BY ANIMAL_TYPE ASC

GROUP BY에 조건달기
WHERE은 <FROM 테이블명>에 쓰는 거임
GROUP BY에는 HAVING으로 조건을 달아줘야 한다.

SELECT NAME, COUNT(NAME)
FROM ANIMAL_INS
GROUP BY NAME
*HAVING COUNT(NAME) > 1*

SELECT HOUR(DATETIME) AS HOUR, COUNT(NAME) AS COUNT
FROM ANIMAL_OUTS
WHERE HOUR(DATETIME) between 9 and 19
GROUP BY HOUR(DATETIME)
ORDER BY 1

SELECT hour(datetime) as HOUR, count(datetime) as COUNT
from animal_outs
where hour(datetime) between 9 and 19
group by hour(datetime)
order by 1;

뭐가 다른지 모르겠는데 안된다 ..