SELECT
  p.PORT_CODE as '港コード',
  p.PORT_NAME as '港名',
  income as '入国者数',
  outcome as '出国者数',
  income - outcome as '差分'
FROM (
  SELECT
    PORT_CODE,
    GROUP_CODE,
    SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END) as income,
    SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) as outcome
  FROM
    IMMIGRATION AS i
  WHERE GROUP_CODE = 120
  GROUP BY i.PORT_CODE, GROUP_CODE
) as i
  LEFT JOIN PORT AS p
  ON i.PORT_CODE = p.PORT_CODE
WHERE
  income > outcome
ORDER BY income - outcome DESC