SELECT PREFECTURE.PF_CODE AS CODE, PF_NAME AS NAME, (DRINKER_NUM / TOTAL_NUM) AS PERCENTAGE
FROM 
(SELECT PF_CODE, SUM(AMT) AS DRINKER_NUM
FROM DRINK_HABITS
WHERE CATEGORY_CODE = '120' AND GENDER_CODE != '1'
GROUP BY PF_CODE) AS T1
LEFT JOIN
(SELECT PF_CODE, SUM(AMT) AS TOTAL_NUM
FROM DRINK_HABITS
WHERE CATEGORY_CODE = '110' AND GENDER_CODE != '1'
GROUP BY PF_CODE) AS T2
ON T1.PF_CODE = T2.PF_CODE
LEFT JOIN PREFECTURE
ON T1.PF_CODE = PREFECTURE.PF_CODE