SELECT
    IMM1.PORT_CODE AS 港コード,
    PT.PORT_NAME AS 港名,
    IMM1.AMT AS 入国者数,
    IMM2.AMT AS 出国者数,
    (IMM1.AMT - IMM2.AMT) AS 差分
FROM
    IMMIGRATION AS IMM1
	INNER JOIN PORT AS PT ON IMM1.PORT_CODE = PT.PORT_CODE
	INNER JOIN IMMIGRATION AS IMM2
	    ON IMM1.PORT_CODE = IMM2.PORT_CODE
	    AND IMM2.GROUP_CODE = '120'
	    AND IMM2.KIND_CODE = '120'
WHERE IMM1.GROUP_CODE = '120' AND IMM1.KIND_CODE = '110'
ORDER BY 差分 DESC, 港コード DESC;