WITH
    t AS (
    SELECT
        PORT_CODE
        ,SUM(CASE WHEN GROUP_CODE = '120' AND KIND_CODE = '110' THEN AMT ELSE 0 END) NYUKOKU
        ,SUM(CASE WHEN GROUP_CODE = '120' AND KIND_CODE = '120' THEN AMT ELSE 0 END) SHUKKOKU
    FROM
        IMMIGRATION
    GROUP BY
        PORT_CODE
    )
SELECT
    t.PORT_CODE "港コード"
    ,port.PORT_NAME "港名"
    ,t.NYUKOKU "入国者数"
    ,t.SHUKKOKU "出国者数"
    ,t.NYUKOKU - t.SHUKKOKU "差分"
FROM
    t
LEFT JOIN
    PORT port
    ON t.PORT_CODE = port.PORT_CODE
WHERE
    t.NYUKOKU - t.SHUKKOKU > 0
ORDER BY
    t.NYUKOKU - t.SHUKKOKU DESC
    ,t.PORT_CODE DESC