查询所有上级条目

SELECT @r AS _id,
(SELECT @r := pid FROM table WHERE id = _id) AS pid,
@l := @l + 1 AS lvl FROM (SELECT @r := {$id},@l := -1) vars,table h WHERE @r <> 0
) T1 JOIN table T2 ON T1._id = T2.id WHERE T1.lvl > 0 AND T1.lvl < {$level} ORDER BY T1.lvl DESC