SELECT
    DISTRICT_CODE as 地区コード,
    CASE 
        WHEN DISTRICT_NAME is null OR DISTRICT_NAME = "" THEN "不明"
        ELSE DISTRICT_NAME
    END as 地区名,
    TOTAL_AMT as 総数,
    MALE_AMT as 男性数,
    FEMALE_AMT as 女性数
FROM
    POPULATION