[プログラマーSQLハイスコアKit]養子縁組の視点を得る(1)(MySQL)

1.問題の説明

SQL文を実行する場合、データは次のようになります.

2.関連概念

3.正解と解答

SELECT HOUR(DATETIME) FROM ANIMAL_OUTS GROUP BY HOUR(DATETIME);

SELECT HOUR(DATETIME), COUNT(ANIMAL_ID)
FROM ANIMAL_OUTS
GROUP BY HOUR(DATETIME);

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

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

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