SELECT
   T1.PORT_CODE AS "港コード"
  ,T2.PORT_NAME AS "港名"
  ,SUM(CASE WHEN T1.KIND_CODE="110" THEN T1.AMT ELSE 0 END)  AS "入国者数"
  ,SUM(CASE WHEN T1.KIND_CODE="120" THEN T1.AMT ELSE 0 END)  AS "出国者数"
  ,SUM(CASE WHEN T1.KIND_CODE="110" THEN T1.AMT ELSE 0 END) - SUM(CASE WHEN T1.KIND_CODE="120" THEN T1.AMT ELSE 0 END) AS "差分"
FROM
  IMMIGRATION AS T1
INNER JOIN
  PORT AS T2 ON T1.PORT_CODE=T2.PORT_CODE
WHERE
  T1.GROUP_CODE = "120"
GROUP BY
  T1.PORT_CODE
HAVING
  "差分" > 0
ORDER BY
   "差分" DESC
  ,T1.PORT_CODE DESC