[SQL문제풀기] 월별 잡은 물고기 수 구하기

Jan 18, 2025

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SELECT COUNT(ID) FISH_COUNT , MONTH(TIME) MONTH
FROM FISH_INFO
GROUP BY 2
ORDER BY 2 ASC

: MySQL의 ONLY_FULL_GROUP_BY SQL 모드에서는 GROUP BY 절에 포함되지 않은 비집계 열을 SELECT 또는 ORDER BY 절에서 사용할 수 없다.


SELECT COUNT(ID) FISH_COUNT , CAST(DATE_FORMAT(TIME,'%m') AS UNSIGNED) MONTH
FROM FISH_INFO
GROUP BY 2
ORDER BY 2 ASC


SELECT COUNT(ID) FISH_COUNT , CONVERT(DATE_FORMAT(TIME,'%m'),UNSIGNED) MONTH
FROM FISH_INFO
GROUP BY 2
ORDER BY 2 ASC

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형변환 함수들 CAST , CONVERT

CAST(COLUMN AS UNSIGNED) : 컬럼을 숫자로 변환

CAST ( COLUMN AS data_type [ ( length ) ] )

CONVERT ( COLUMN, data_type [ ( length ) ] )

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