SELECT
  i.PORT_CODE AS "港コード",
  p.PORT_NAME AS "港名",
  SUM(CASE WHEN i.KIND_CODE = "110" THEN IFNULL(AMT, 0) ELSE 0 END) AS "入国者数",
  SUM(CASE WHEN i.KIND_CODE = "120" THEN IFNULL(AMT, 0) ELSE 0 END) AS "出国者数",
  IFNULL(SUM(CASE WHEN i.KIND_CODE = "110" THEN IFNULL(AMT, 0) ELSE 0 END),0) - IFNULL(SUM(CASE WHEN i.KIND_CODE = "120" THEN IFNULL(AMT, 0) ELSE 0 END),0) AS "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_NAME
HAVING
  i.GROUP_CODE IN("120")
  AND g.GROUP_CODE IN("120")
  AND IFNULL(SUM(CASE WHEN i.KIND_CODE = "110" THEN IFNULL(AMT, 0) ELSE 0 END),0) - IFNULL(SUM(CASE WHEN i.KIND_CODE = "120" THEN IFNULL(AMT, 0) ELSE 0 END),0) > 0
ORDER BY
  "差分" DESC,
  i.PORT_CODE DESC
;