select 
    popu.PF_CODE as "都道府県コード",
    test.PF_NAME as "都道府県名",
    test.TOTAL_AMT as "2015",
    popu.TOTAL_AMT as "2020"
from
    (
        select
            p.PF_CODE,
            p.TOTAL_AMT,
            pr.PF_NAME
        from
            POPU_TRANSITION as p
            inner join
                PREFECTURE as pr
            on
                p.PF_CODE = pr.PF_CODE
        where
            p.SURVEY_YEAR = "2015"
    ) as test
inner join
    POPU_TRANSITION as popu
on
    test.PF_CODE = popu.PF_CODE
where
    popu.SURVEY_YEAR = '2020'
order by
    popu.PF_CODE asc;