mysql 根据子级ID获取全部上级

1、查询所有上级

SELECT
    T0.*
FROM
    (
        SELECT
            @r AS _id,
            (
                SELECT
                    @r := parent_id
                FROM
                    t_user
                WHERE
                    id = _id
            ) AS parent_id1,
            @l := @l + 1 AS lvl
        FROM
            (SELECT @r := 2, @l := 0) vars, -- 这里的2是用户id
            t_user h
        WHERE
            @r <> 0
    ) T0
JOIN t_user T1 ON T0._id = T1.id
ORDER BY id;

2、查询所有下级

SELECT
    *
FROM
    (
        SELECT
            @ids AS _ids,
            (
                SELECT
                    @ids := GROUP_CONCAT(id)
                FROM
                    t_user
                WHERE
                    FIND_IN_SET(parent_id, @ids)
            ) AS cids,
            @l := @l + 1 AS lvl
        FROM
            t_user,
            (SELECT @ids := 1, @l := 0) b -- 这里的1是用户id
        WHERE
            @ids IS NOT NULL
    ) id,
    t_user DATA
WHERE
    FIND_IN_SET(DATA .id, id._ids)
ORDER BY
    lvl,
    id