[SQL문제풀기] 분기별 분화된 대장균의 개체 수 구하기

문제

MYSQL

내가 작성한 정답

SELECT QUARTER, COUNT(*) ECOLI_COUNT
FROM (SELECT CASE WHEN MONTH(DIFFERENTIATION_DATE) IN (1,2,3) THEN '1Q'
             WHEN MONTH(DIFFERENTIATION_DATE) IN (4,5,6) THEN '2Q'
             WHEN MONTH(DIFFERENTIATION_DATE) IN (7,8,9) THEN '3Q'
             WHEN MONTH(DIFFERENTIATION_DATE) IN (10,11,12) THEN '4Q' END QUARTER
      FROM ECOLI_DATA) Q
GROUP BY QUARTER
ORDER BY 1;