my database table user_tree looks like this. This is a left-right value tree, where Level represents the depth of the tree, Lft is the left value, and Rgt is the right value.

< table > < tbody > < tr class= "firstRow" > < th width= "147" > Userid < / th > < th width= "147" > Name < / th > < th width= "147" > Lft < / th > < th width= "147" > Rgt < / th > < th colspan= "1" rowspan= "1" width= "147" > Level < / th > < / tr > < tr > < td width= "147" > 1001 < / td > < td width= "147" > Wang < / td > < td width= "147" > one < / td > < td width= "147" > sixteen < / td > < td colspan= "1" rowspan= "1" width= "147" > one < / td > < / tr > < tr > < td width= "147" > 1002 < / td > < td width= "147" > Li < / td > < td width= "147" > two < / td > < td width= "147" > seven < / td > < td colspan= "1" rowspan= "1" width= "147" > two < / td > < / tr > < tr > < td width= "147" > 1003 < / td > < td width= "147" > Wlm < / td > < td width= "147" > eight < / td > < td width= "147" > fifteen < / td > < td colspan= "1" rowspan= "1" width= "147" > two < / td > < / tr > < tr > < td width= "147" > 1005 < / td > < td width= "147" > Bander < / td > < td width= "147" > three < / td > < td width= "147" > four < / td > < td colspan= "1" rowspan= "1" width= "147" > three < / td > < / tr > < tr > < td width= "147" > 1008 < / td > < td width= "147" > Qipl < / td > < td width= "147" > five < / td > < td width= "147" > six < / td > < td colspan= "1" rowspan= "1" width= "147" > three < / td > < / tr > < tr > < td width= "147" > 1007 < / td > < td width= "147" > Buliao < / td > < td width= "147" > nine < / td > < td width= "147" > twelve < / td > < td colspan= "1" rowspan= "1" width= "147" > three < / td > < / tr > < tr > < td width= "147" > 1009 < / td > < td width= "147" > Wumao < / td > < td width= "147" > thirteen < / td > < td width= "147" > fourteen < / td > < td colspan= "1" rowspan= "1" width= "147" > three < / td > < / tr > < tr > < td colspan= "1" rowspan= "1" > 1013 < / td > < td colspan= "1" rowspan= "1" > Zhangsan < / td > < td colspan= "1" rowspan= "1" > ten < / td > < td colspan= "1" rowspan= "1" > eleven < / td > < td colspan= "1" rowspan= "1" > four < / td > < / tr > < / tbody > < / table >

Organization chart:

how can it be implemented with php? if you give a UserID value arbitrarily, it can be organized into a multi-dimensional array structure.
for example, if I enter a function aaa (userid=1003), I can return a multi-dimensional array of all descendant nodes under 1003. Use only one query, can not cycle to the database query, the server can not stand. No more than 2 queries, and the results will appear. Return up to 4 layers. For example, enter 1003. Query to 1003, at layer 2, then query to layer 6 at most.

query all descendant nodes of 1003 nodes is like this, left and right value tree reference

SELECT * FROM user_tree WHERE Lft >= 8 AND Lft <= 15 AND Level<=6 ORDER BY Level ASC

array(
    "userid" => "1003",
    "name" => "wlm",
    "children" => array(
        0 => array(
            "userid" => "1007",
            "name" => "buliao",
            "children" => array(
                0 => array(
                    "userid" => "1013",
                    "name" => "zhangsan"
                )
            ) ,
        1 => array(
            "userid" => "1009",
            "name" => "wumao"
            ) ,
        ) ,
    ) ,
);

I"ve been thinking about it for 3 days, and I can"t figure it out, so ask for help from the seniors here.