SELECT A.PORT_CODE AS 港コード
     , B.PORT_NAME AS 港名
     , (SELECT SUM(AMT)
          FROM IMMIGRATION
         WHERE GROUP_CODE = '120' AND KIND_CODE = '110'
         GROUP BY PORT_CODE) AS 入国者数
     , (SELECT SUM(AMT)
          FROM IMMIGRATION
         WHERE GROUP_CODE = '120' AND KIND_CODE = '120'
         GROUP BY PORT_CODE) AS 出国者数
     , (SELECT SUM(AMT)
          FROM IMMIGRATION
         WHERE GROUP_CODE = '120' AND KIND_CODE = '110'
         GROUP BY PORT_CODE) - 
       (SELECT SUM(AMT)
          FROM IMMIGRATION
         WHERE GROUP_CODE = '120' AND KIND_CODE = '120'
         GROUP BY PORT_CODE) AS 差分
  FROM IMMIGRATION AS A
 INNER JOIN PORT AS B
    ON A.PORT_CODE = B.PORT_CODE
 INNER JOIN GRP AS C
    ON A.GROUP_CODE - C.GROUP_CODE
 ORDER BY  差分 DESC , 港コード DESC