SELECT
IN_TBL.PORT_CODE AS '港コード',
PORT.PORT_NAME AS '港名',
IN_TBL.AMT AS '入国者数',
OUT_TBL.AMT AS '出国者数',
OUT_TBL.AMT - IN_TBL.AMT AS '差分'
FROM (SELECT PORT_CODE, AMT FROM IMMIGRATION WHERE KIND_CODE = '110') AS IN_TBL
JOIN (SELECT PORT_CODE, AMT FROM IMMIGRATION WHERE KIND_CODE = '120') AS OUT_TBL ON OUT_TBL.PORT_CODE = IN_TBL.PORT_CODE
JOIN PORT ON PORT.PORT_CODE = IN_TBL.PORT_CODE
WHERE OUT_TBL.AMT > IN_TBL.AMT
ORDER BY '差分' DESC, IN_TBL.PORT_CODE DESC 
;