[프로그래머스] 입양 시각 구하기(2) SET @hour := -1; -- 변수 선언 SELECT (@hour := @hour + 1) as HOUR, (SELECT COUNT(*) FROM ANIMAL_OUTS WHERE HOUR(DATETIME) = @hour) as COUNT FROM ANIMAL_OUTS WHERE @hour < 23 알고리즘 2023.10.07