select V_A.PORT_CODE as 港コード, PORT_NAME as 港名, 入国者数, 出国者数, 差分 from 
    (select PORT_CODE, sum(iif(KIND_CODE = '110', AMT, 0)) as 入国者数, sum(iif(KIND_CODE = '120', AMT, 0)) as 出国者数, sum(iif(KIND_CODE = '110', AMT, 0)) - sum(iif(KIND_CODE = '120', AMT, 0)) as 差分
        from IMMIGRATION where GROUP_CODE = '120' 
        group by PORT_CODE order by 差分 desc, PORT_CODE desc) as V_A, PORT on V_A.PORT_CODE = PORT.PORT_CODE  
    where 差分 > 0;