SELECT
  t1.PORT_CODE AS '港コード'
  , t1.PORT_NAME AS '港名'
  , t2.AMT AS '入国者数'
  , t3.AMT AS '出国者数'
  , t2.AMT - t3.AMT AS '差分'
FROM
  PORT t1
INNER JOIN
  (SELECT PORT_CODE, AMT FROM IMMIGRATION WHERE KIND_CODE = '110' AND GROUP_CODE = '120') t2
  ON
    t1.PORT_CODE = t2.PORT_CODE
INNER JOIN
  (SELECT PORT_CODE, AMT FROM IMMIGRATION WHERE KIND_CODE = '120' AND GROUP_CODE = '120') t3
  ON
    t1.PORT_CODE = t3.PORT_CODE
WHERE t2.AMT - t3.AMT > 0
ORDER BY
  t2.AMT - t3.AMT DESC
  , t1.PORT_CODE DESC
;