SELECT
    IMG.port_code AS 港コード
    , PT.port_name AS 港名
    , SUM( 
        CASE 
            WHEN IMG.kind_code = '110' 
                THEN IMG.amt 
            ELSE 0 
            END
    ) AS 入国者数
    , SUM( 
        CASE 
            WHEN IMG.kind_code = '120' 
                THEN IMG.amt 
            ELSE 0 
            END
    ) AS 出国者数
    , SUM( 
        CASE 
            WHEN IMG.kind_code = '110' 
                THEN amt 
            ELSE 0 
            END
    ) - SUM( 
        CASE 
            WHEN IMG.kind_code = '120' 
                THEN amt 
            ELSE 0 
            END
    ) AS 差分 
FROM
    immigration IMG 
    INNER JOIN port PT 
        ON IMG.port_code = PT.port_code 
GROUP BY
    IMG.port_code 
HAVING
    差分 > 0 
ORDER BY
     SUM( 
        CASE 
            WHEN IMG.kind_code = '110' 
                THEN amt 
            ELSE 0 
            END
    ) - SUM( 
        CASE 
            WHEN IMG.kind_code = '120' 
                THEN amt 
            ELSE 0 
            END
    ) DESC
    , IMG.port_code DESC