[SQL]프로그래머스 : 입양 시각 구하기(1)(DATE_FORMAT,TO_CHAR)

1. 문제

https://programmers.co.kr/learn/courses/30/lessons/59412 

코딩테스트 연습 - 입양 시각 구하기(1)

2. 풀이

• 시간대 구하기 :
  • MYSQL  : DATE_FORMAT
  • ORACLE : TO_CHAR
• 시간대별로 건수 구하기 : GROUP BY, COUNT
• 시간대 순으로 정렬 : ORDER BY

3. 답안

 --MYSQL
SELECT DATE_FORMAT(DATETIME, '%H') AS HOUR, COUNT(1) AS COUNT 
FROM ANIMAL_OUTS
WHERE DATE_FORMAT(DATETIME, '%H') BETWEEN '09' AND '19'
GROUP BY DATE_FORMAT(DATETIME, '%H') 
ORDER BY HOUR
;

--ORACLE
SELECT TO_CHAR(DATETIME, 'HH24') AS HOUR, COUNT(1) AS COUNT 
FROM ANIMAL_OUTS
WHERE TO_CHAR(DATETIME, 'HH24') BETWEEN '09' AND '19'
GROUP BY TO_CHAR(DATETIME, 'HH24') 
ORDER BY HOUR
;