值得记录学习的SQL语句

SELECT
	D.*
FROM
	(
		SELECT
			*
		FROM
			(
				SELECT
					*
				FROM
					(
						SELECT
							@ROWNUM := @ROWNUM + 1 AS ROWNUM,
							H.*
						FROM
							qc_approval_history H,
							(SELECT @ROWNUM := 0) A
						WHERE
							APPROVAL_STATUS = 0
						ORDER BY
							H.`FOREIGN_ID`,
							H.`APPROVER_ORDER`
					) AH
				GROUP BY
					AH.FOREIGN_ID
				ORDER BY
					AH.ROWNUM
			) B
		WHERE
			(
				B.APPROVER IS NULL
				OR B.APPROVER = ''
				OR B.APPROVER = 'QM0001'
			)
		AND B.APPROVER_ROLE IN ('质检经理')
	) D
UNION ALL
	SELECT
		M.*
	FROM
		(
			SELECT
				@ROWNUM := @ROWNUM + 1 AS ROWNUM,
				J.*
			FROM
				qc_approval_history J
			WHERE
				APPROVER = 'QM0001'
			AND APPROVAL_STATUS != '0'
			ORDER BY
				CAST(APPROVAL_TIME AS datetime) DESC
		) M

条件：1.查询审批流中未审批

          2.的最小的审批顺序的

          3.是我审批的，

          4.下面是我已经审批的按时间倒序排