[GROUP BY/LEVEL4] 언어별 개발자 분류하기 (MySQL)

MySQL

SELECT
    CASE
     WHEN (SKILL_CODE & (SELECT SUM(CODE) FROM SKILLCODES WHERE CATEGORY LIKE 'FRONT%')) 
          AND SKILL_CODE & (SELECT CODE FROM SKILLCODES WHERE NAME = 'PYTHON') THEN 'A'
     WHEN SKILL_CODE & (SELECT CODE FROM SKILLCODES WHERE NAME = 'C#') THEN 'B'
     WHEN SKILL_CODE & (SELECT SUM(CODE) FROM SKILLCODES WHERE CATEGORY LIKE 'FRONT%') THEN 'C'
    ELSE NULL
    END AS GRADE
,ID, EMAIL
FROM DEVELOPERS
GROUP BY GRADE, ID, EMAIL
HAVING GRADE IS NOT NULL
ORDER BY GRADE, ID

비트 연산 안하고 싶어요.