[SQL 문제 풀이] 연도별 대장균 크기의 편차 구하기

SELECT 
    YEAR(A.DIFFERENTIATION_DATE) AS 'YEAR',
    B.MAX_SIZE - A.SIZE_OF_COLONY AS 'YEAR_DEV',
    A.ID
FROM
    ECOLI_DATA AS A
        JOIN
    (SELECT 
        YEAR(DIFFERENTIATION_DATE) AS YEAR,  MAX(SIZE_OF_COLONY) AS 'MAX_SIZE'
    FROM
        ECOLI_DATA
    GROUP BY YEAR(DIFFERENTIATION_DATE)) B 
    ON YEAR(A.DIFFERENTIATION_DATE) = B.YEAR
ORDER BY YEAR , YEAR_DEV;