SELECT
   IC.PORT_CODE AS 港コード
  ,P.PORT_NAME AS 港名
  ,IC.AMT  AS 入国者数
  ,OC.AMT  AS 出国者数
  ,IC.AMT  - OC.AMT  AS 差分
FROM
  IMMIGRATION IC
  INNER JOIN
  IMMIGRATION OC
  ON 
    IC.PORT_CODE = OC.PORT_CODE
  INNER JOIN
  PORT P
  ON IC.PORT_CODE = P.PORT_CODE
WHERE
      IC.KIND_CODE='110'
  AND OC.KIND_CODE='120'
  AND IC.GROUP_CODE='120'
  AND OC.GROUP_CODE='120'
ORDER BY
  差分 DESC,IC.PORT_CODE DESC
  
  ;