입양 시각 구하기(2)

• 문제
  
  
• 정답

SET @HOURS = -1;
SELECT (@HOURS := @HOURS+1) HOUR,
    (SELECT COUNT(*) FROM ANIMAL_OUTS WHERE HOUR(DATETIME) = @HOURS) COUNT
FROM ANIMAL_OUTS 
WHERE @HOURS < 23

• 결과