SELECT
PORT_CODE,
PORT_NAME,
ENTRY,
EXIT,
ENTRY - EXIT AS DIFFERENCE
FROM
(SELECT
t1.PORT_CODE,
PORT_NAME,
SUM(CASE
WHEN KIND_CODE = '110'
THEN AMT
ELSE 0
END) AS ENTRY,
SUM(
CASE
WHEN KIND_CODE = '120'
THEN AMT
ELSE 0
END) AS EXIT
FROM
IMMIGRATION t1
LEFT JOIN
PORT t2
ON
t1.PORT_CODE = t2.PORT_CODE
WHERE
GROUP_CODE = '120'
GROUP BY
t1.PORT_CODE)
WHERE DIFFERENCE > 0
ORDER BY
DIFFERENCE DESC,
PORT_CODE DESC