WITH IN_TABLE AS (
SELECT
    *
FROM
    IMMIGRATION
WHERE
    KIND_CODE = '110'
AND
    GROUP_CODE ='120'
)
, OUT_TABLE AS(
SELECT
    *
FROM
    IMMIGRATION
WHERE
    KIND_CODE ='120'
    AND
    GROUP_CODE ='120'
)

SELECT
    i.PORT_CODE as 港コード,
    p.PORT_NAME as 港名,
    i.AMT as 入国者数,
    o.AMT as 出国者数,
    i.AMT - o.AMT as 差分
FROM
    IN_TABLE as i
JOIN
    OUT_TABLE as o
ON
    i.PORT_CODE = o.PORT_CODE
JOIN
    PORT as p
ON
    i.PORT_CODE = p.PORT_CODE
ORDER BY
    5 DESC,
    1 DESC