[Level4] RECURSIVE WITH

in 코딩테스트 on SQL




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programmers 


WITH RECURSIVE TEMP AS (
        SELECT 0 AS NUM
     UNION ALL
        SELECT NUM+1 FROM TEMP
         WHERE NUM < 23)


   SELECT T.NUM AS HOUR, COUNT(O.ANIMAL_ID) AS COUNT
     FROM TEMP T
LEFT JOIN ANIMAL_OUTS O
       ON T.NUM = HOUR(O.DATETIME)
 GROUP BY T.NUM
 ORDER BY T.NUM