SELECT
  P.PORT_CODE AS "港コード",
  P.PORT_NAME AS "港名",
  I110.AMT AS "入国者数",
  I120.AMT AS "出国者数",
  I110.AMT - I120.AMT AS "差分"
FROM PORT AS P
JOIN IMMIGRATION AS I110 ON I110.GROUP_CODE = '120' AND I110.KIND_CODE = '110' AND P.PORT_CODE = I110.PORT_CODE
JOIN IMMIGRATION AS I120 ON I120.GROUP_CODE = '120' AND I120.KIND_CODE = '120' AND P.PORT_CODE = I120.PORT_CODE
WHERE I110.AMT - I120.AMT > 0
ORDER BY "差分" DESC, "港コード" DESC