SELECT A.PORT_CODE as "港コード", PORT_NAME as "港名", A.AMT as "入国者数", B.AMT as "出国者数", A.AMT - B.AMT as "差分" FROM 
(SELECT PORT_CODE, AMT, GROUP_CODE FROM IMMIGRATION WHERE KIND_CODE = 110) as A, (SELECT PORT_CODE, AMT, GROUP_CODE FROM IMMIGRATION WHERE KIND_CODE = 120) as B, PORT
WHERE A.PORT_CODE = B.PORT_CODE AND PORT.PORT_CODE = A.PORT_CODE AND 差分 >= 1 AND A.GROUP_CODE = 120 AND B.GROUP_CODE = 120 ORDER BY 差分 DESC, A.PORT_CODE DESC