WITH mart AS(
  SELECT
    IMMIGRATION.PORT_CODE,
    PORT_NAME,
    MAX(CASE WHEN KIND_CODE = 110 THEN AMT ELSE 0 END) AS IN_AMT,
    MAX(CASE WHEN KIND_CODE = 120 THEN AMT ELSE 0 END) AS OUT_AMT

  FROM
    IMMIGRATION
  INNER JOIN
    PORT
  ON
    IMMIGRATION.PORT_CODE = PORT.PORT_CODE
  WHERE
    GROUP_CODE = 120
  GROUP BY
    IMMIGRATION.PORT_CODE
)

SELECT
  PORT_CODE AS 港コード,
  PORT_NAME AS 港名,
  IN_AMT AS 入国者数,
  OUT_AMT AS 出国者数,
  IN_AMT - OUT_AMT AS 差分
FROM
  mart
WHERE
  IN_AMT - OUT_AMT > 0
ORDER BY
  差分 DESC,
  港コード DESC