SELECT
    I.PORT_CODE AS 港コード,
    P.PORT_NAME AS 港名,
    SUM(CASE WHEN I.KIND_CODE = '110' THEN I.AMT END) AS 入国者数,
    SUM(CASE WHEN I.KIND_CODE = '120' THEN I.AMT END) AS 出国者数,
    SUM(CASE WHEN I.KIND_CODE = '110' THEN I.AMT END) 
    -
    SUM(CASE WHEN I.KIND_CODE = '120' THEN I.AMT END) AS 差分
FROM
    IMMIGRATION AS I
JOIN
    PORT AS P
ON
    I.PORT_CODE = P.PORT_CODE
JOIN
    GRP AS G
ON
    I.GROUP_CODE = G.GROUP_CODE
GROUP BY
    I.PORT_CODE
ORDER BY
    差分 DESC,
    I.PORT_CODE DESC