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