WITH agg AS(
  SELECT
    T1.PORT_CODE 
    ,PORT_NAME
    --,KIND_CODE
    --,AMT
    ,CASE WHEN KIND_CODE = 110 THEN AMT ELSE 0 END AS in_uu --外国人入国者のAMT 
    ,CASE WHEN KIND_CODE = 120 THEN AMT ELSE 0 END AS out_uu --外国人出国者のAMT
  FROM
    IMMIGRATION T1
    LEFT JOIN GRP ON T1.GROUP_CODE = GRP.GROUP_CODE
    LEFT JOIN PORT ON T1.PORT_CODE = PORT.PORT_CODE
  WHERE
    GRP.GROUP_NAME = '外国人'
)
SELECT
  PORT_CODE AS '港コード'
  ,PORT_NAME AS '港名'
  ,MAX(in_uu) AS '入国者数'
  ,MAX(out_uu) AS '出国者数'
  ,MAX(in_uu - out_uu) AS '差分'
FROM
  agg
WHERE
  in_uu > out_uu
GROUP BY
  PORT_CODE
ORDER BY
  in_uu - out_uu DESC
  ,PORT_CODE DESC
;