SELECT
  p.PORT_CODE AS "港コード",
  p.PORT_NAME AS "港名",
  SUM(CASE WHEN i.KIND_CODE = "110" THEN AMT ELSE 0 END) "入国者数",
  SUM(CASE WHEN i.KIND_CODE = "120" THEN AMT ELSE 0 END) "出国者数",
  SUM(CASE WHEN i.KIND_CODE = "110" THEN AMT ELSE 0 END) - SUM(CASE WHEN i.KIND_CODE = "120" THEN AMT ELSE 0 END) "差分"
FROM
  IMMIGRATION i
INNER JOIN
  GRP g ON i.GROUP_CODE = g.GROUP_CODE
INNER JOIN
  PORT p ON p.PORT_CODE = i.PORT_CODE
GROUP BY
  p.PORT_CODE,
  p.PORT_NAME
ORDER BY
  "差分",
  p.PORT_CODE
;