select  
PORT.PORT_CODE as '港コード',
PORT.PORT_NAME as '港名',
IN_ATM.AMT as '入国者数',
OUT_ATM.AMT as '出国者数',
IN_ATM.AMT - OUT_ATM.AMT as '差分'
from PORT
inner join IMMIGRATION as IN_ATM  
on 
IN_ATM.PORT_CODE = PORT.PORT_CODE and IN_ATM.KIND_CODE = '110' 
inner join IMMIGRATION as OUT_ATM  
on 
OUT_ATM.PORT_CODE = PORT.PORT_CODE and OUT_ATM.KIND_CODE = '120'  
where (IN_ATM.GROUP_CODE = '120' and OUT_ATM.GROUP_CODE = '120') and IN_ATM.AMT > OUT_ATM.AMT
ORDER BY 
"差分" DESC,
"港コード" DESC