프로그래머스 - ORACLE SQL (GROUP BY)

고양이와 개는 몇마리 있을까

SELECT animal_type, count(*)

FROM animal_ins

GROUP BY animal_type

ORDER BY animal_type

동명 동물 수 찾기

SELECT name,count

FROM

(SELECT name, count(name) count

FROM animal_ins

WHERE name is not NULL

GROUP BY name

ORDER BY name)

WHERE count >=2

==================

SELECT name, count(*)

FROM animal_ins

WHERE name is not NULL

GROUP BY name

HAVING count(*)>=2

ORDER BY name

입양 시각 구하기(1)

SELECT HOUR, count(HOUR)

FROM

(SELECT to_char(datetime,'HH24') HOUR

FROM animal_outs)

WHERE HOUR >=9 and HOUR<=19

GROUP BY HOUR

ORDER BY HOUR

입양 시각 구하기(2) PASS