SELECT
    I.PORT_CODE AS 港コード,
    P.PORT_NAME AS 港名,
    SUM(CASE I.KIND_CODE WHEN 110 THEN I.AMT END) AS 入国者数,
    SUM(CASE I.KIND_CODE WHEN 120 THEN I.AMT END) AS 出国者数,
    SUM(CASE I.KIND_CODE WHEN 110 THEN I.AMT END) - 
    SUM(CASE I.KIND_CODE WHEN 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
WHERE
    I.GROUP_CODE = 120
GROUP BY
    I.PORT_CODE,
    P.PORT_NAME
ORDER BY
    差分 DESC,
    港コード DESC;