SELECT
    i.PORT_CODE as '港コード',
    p.PORT_NAME as '港名',
    SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END) as '入国者数',
    SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) as '出国者数',
    SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END)
      - SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) as '差分'
FROM IMMIGRATION as i 
INNER JOIN GRP as g ON i.GROUP_CODE = g.GROUP_CODE
INNER JOIN PORT as p ON i.PORT_CODE = p.PORT_CODE
WHERE i.GROUP_CODE = '120'
GROUP BY i.PORT_CODE, p.PORT_NAME
HAVING SUM(CASE WHEN KIND_CODE = '110' THEN AMT ELSE 0 END)
      - SUM(CASE WHEN KIND_CODE = '120' THEN AMT ELSE 0 END) >= 0
ORDER BY 5 DESC, 1 DESC