SELECT 
    PF.PF_CODE AS 都道府県コード,
    PF.PF_NAME AS 都道府県名,
    PT.TOTAL_AMT AS 総人口2015年,
    PT_2020.TOTAL_AMT AS 総人口2020年,
    ROUND( 
        -- 計算項目がINTEGER型なのでCAST関数でREAL型に変換して計算しています
        CAST(PT_2020.TOTAL_AMT AS REAL) / CAST(PT.TOTAL_AMT AS REAL)
        * 100
    ) AS 人口増加率
    
    
FROM
    POPU_TRANSITION AS PT
    LEFT JOIN PREFECTURE AS PF 
    ON PF.PF_CODE = PT.PF_CODE
    
    LEFT JOIN POPU_TRANSITION AS PT_2020 
    ON PT_2020.PF_CODE = PT.PF_CODE AND PT_2020.SURVEY_YEAR=2020
    
WHERE
    (PT.SURVEY_YEAR = 2015 AND PT.TOTAL_AMT<PT_2020.TOTAL_AMT)
ORDER BY
    人口増加率 DESC
    , 都道府県コード ASC;
    
;