การดึงข้อมูลล่าสุดเพียงอันเดียวของแต่ละคนในตางรางเดียวกัน

select pcl_id from tb group by request_id order by pcl_id desc

SELECT pcl_id
FROM tb_check_pcl
GROUP BY request_id
ORDER BY pcl_id DESC 

SELECT MAX(pcl_id), request_id
FROM tb_check_pcl
GROUP BY request_id

SELECT
	*
FROM
	(
		SELECT
		a.*, (@i := @i + 1) AS Row_Number
FROM
		tb_check_pcl AS a
		INNER JOIN(SELECT @i := 0) AS Dummy1
ORDER BY
		Row_Number DESC
	)  AS Dummy2
GROUP BY request_id