mysql递归查询，根据子类查询所有父类

1、根据子类查询父类

SELECT
	h2.* 
FROM
	(
	SELECT
		@r AS _id,
		( SELECT @r := parent_id FROM sys_safety_partial WHERE id = _id ) AS parent_id,
		@l := @l + 1 AS lvl 
	FROM
		( SELECT @r := 'a55288a9b5eb15e1653339fee1bc7ed2', @l := 0 ) vars,
		sys_safety_partial h 
	) T1
	JOIN sys_safety_partial h2 ON T1._id = h2.id