SELECT
    SUB.PORT_CODE AS '港コード',
    PORT_NAME AS '港名',
    IN_AMT AS '入国者数',
    OUT_AMT AS '出国者数',
    IN_AMT - OUT_AMT AS '差分'
FROM (
    SELECT
        PORT_CODE,
        MAX(CASE WHEN KIND_CODE='110' THEN AMT ELSE 0 END) AS IN_AMT,
        MAX(CASE WHEN KIND_CODE='120' THEN AMT ELSE 0 END) AS OUT_AMT
    FROM
        IMMIGRATION
    WHERE
        GROUP_CODE = '120'
    GROUP BY
        PORT_CODE
    ) AS SUB
    INNER JOIN PORT
        ON PORT.PORT_CODE=SUB.PORT_CODE
WHERE
    IN_AMT > OUT_AMT
ORDER BY
    差分 DESC,
    港コード DESC
    ;