WITH come AS(
    SELECT
        p.PORT_CODE,
        SUM(i.AMT) AS 入国者数
    FROM
        PORT AS p,
        IMMIGRATION AS i
    WHERE
        p.PORT_CODE = i.PORT_CODE AND
        i.KIND_CODE = '110' AND
        i.GROUP_CODE = '120'
    GROUP BY
        p.PORT_CODE
),
go AS(
    SELECT
        p.PORT_CODE,
        SUM(i.AMT) AS 出国者数
    FROM
        PORT AS p,
        IMMIGRATION AS i
    WHERE
        p.PORT_CODE = i.PORT_CODE AND
        i.KIND_CODE = '120' AND
        i.GROUP_CODE = '120'
    GROUP BY
        p.PORT_CODE
)

SELECT
    p.PORT_CODE AS 港コード,
    p.PORT_NAME AS 港名,
    come.入国者数,
    go.出国者数,
    (come.入国者数 - go.出国者数) AS 差分
FROM
    PORT AS p,
    come,
    go
WHERE
    p.PORT_CODE = come.PORT_CODE AND
    p.PORT_CODE = go.PORT_CODE AND
    come.入国者数 > go.出国者数
ORDER BY
    差分 DESC,
    港コード DESC