with D_IMM as (
SELECT  PORT_CODE
       ,AMT
       ,GROUP_CODE
FROM    IMMIGRATION
WHERE KIND_CODE  = '110'
AND   GROUP_CODE = '120'
),
E_IMM as (
SELECT  PORT_CODE
       ,AMT
       ,GROUP_CODE
FROM    IMMIGRATION
WHERE KIND_CODE  = '120'
AND   GROUP_CODE = '120'
)
SELECT  PORT.PORT_CODE          AS '港コード'
       ,PORT.PORT_NAME          AS '港名'
       ,D_IMM.AMT               AS '入国者数'
       ,E_IMM.AMT               AS '出国者数'
       ,(D_IMM.AMT - E_IMM.AMT) AS '差分'
FROM    PORT
        LEFT JOIN D_IMM  ON PORT.PORT_CODE = D_IMM.PORT_CODE
        LEFT JOIN E_IMM  ON PORT.PORT_CODE = E_IMM.PORT_CODE
WHERE   D_IMM.AMT > E_IMM.AMT
ORDER BY 5 desc,1 desc;