WITH IMG AS(
    SELECT PORT_CODE, AMT
    FROM IMMIGRATION
    WHERE GROUP_CODE='120' AND KIND_CODE='110'
    ),LV AS(
    SELECT PORT_CODE, AMT
    FROM IMMIGRATION
    WHERE GROUP_CODE='120' AND KIND_CODE='120'
    )

SELECT
    IMG.PORT_CODE AS 港コード,
    PORT_NAME AS 港名,
    IMG.AMT AS 入国者数,
    LV.AMT AS 出国者数,
    IMG.AMT-LV.AMT AS 差分
FROM
    IMG INNER JOIN LV ON LV.PORT_CODE=IMG.PORT_CODE
    INNER JOIN PORT ON PORT.PORT_CODE=IMG.PORT_CODE
WHERE
    IMG.AMT>LV.AMT
ORDER BY
    差分 DESC,
    港コード DESC
;