WITH SUBSUM AS (
    SELECT
        PORT_CODE
      , SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END) AS SUM_IN
      , SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) AS SUM_OUT
    FROM
        IMMIGRATION
    WHERE
        GROUP_CODE = '120'
    GROUP BY
        PORT_CODE
)
SELECT
    T1.PORT_CODE           AS "港コード"
  , M1.PORT_NAME           AS "港名"
  , T1.SUM_IN              AS "入国者数"
  , T1.SUM_OUT             AS "出国者数"
  , T1.SUM_IN - T1.SUM_OUT AS "差分"
FROM
    SUBSUM T1
    LEFT OUTER JOIN PORT M1
        ON T1.PORT_CODE = M1.PORT_CODE
WHERE
    T1.SUM_IN > T1.SUM_OUT
ORDER BY
    差分     DESC
  , 港コード DESC
;