I’ve got a little challenge here for you all, there is the data: CREATE

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Asked: May 31, 20262026-05-31T22:25:09+00:00 2026-05-31T22:25:09+00:00

I’ve got a little challenge here for you all, there is the data: CREATE

0

I’ve got a little challenge here for you all, there is the data:

CREATE TABLE vCategoryTree (
    level1 INT UNSIGNED DEFAULT NULL,
    level2 INT UNSIGNED DEFAULT NULL,
    level3 INT UNSIGNED DEFAULT NULL,
    level4 INT UNSIGNED DEFAULT NULL,
    level5 INT UNSIGNED DEFAULT NULL
);

INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 44, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 45, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 46, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 48, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 49, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 50, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 51, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 52, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 53, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 54, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 55, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 56, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 57, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 58, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 59, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 60, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 62, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 63, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 64, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 65, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 66, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 67, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 68, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 69, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 70, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 10, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 25, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 26, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 11, 12, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 11, 13, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 15, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 16, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 17, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 18, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 19, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 20, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 21, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 22, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 23, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 24, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 27, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 29, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 34, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 37, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 38, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 39, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 41, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 42, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 31, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 35, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 40, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 32, 33, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 32, 36, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 6, 7, NULL, NULL);
INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 6, 8, NULL, NULL);

It is the result of various experiment at transforming an adjacency model to a modified preorder tree taversal model all in MySQL.

What i need to do here, is generate a list from these levels into a row based result tree, for example, i’m looking to get:

The … are just a cut in the expected data so i can provide more of the example without actually pasting the whole thing i need, i’m not expecting … to appear in there.

Hope this is enough…

And NO, i don’t want to do it via PHP…

Thank you

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1 Answer

Editorial Team · Answer 1 · 2026-05-31T22:25:11+00:00

First, let’s load your sample data

mysql> drop database if exists mathieu;
Query OK, 2 rows affected (0.11 sec)

mysql> create database mathieu;
Query OK, 1 row affected (0.00 sec)

mysql> use mathieu
Database changed
mysql> CREATE TABLE vCategoryTree (
    ->     level1 INT UNSIGNED DEFAULT NULL,
    ->     level2 INT UNSIGNED DEFAULT NULL,
    ->     level3 INT UNSIGNED DEFAULT NULL,
    ->     level4 INT UNSIGNED DEFAULT NULL,
    ->     level5 INT UNSIGNED DEFAULT NULL
    -> );
Query OK, 0 rows affected (0.08 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 44, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 45, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 43, 46, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 48, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 49, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 50, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 51, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 52, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 53, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 54, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 55, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 56, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 57, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 58, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 59, NULL);
Query OK, 1 row affected (0.10 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 47, 60, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 62, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 63, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 64, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 65, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 66, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 67, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 68, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 69, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 2, 61, 70, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 10, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 25, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 9, 26, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 11, 12, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 11, 13, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 15, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 16, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 17, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 18, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 19, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 20, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 21, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 22, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 23, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 24, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 4, 14, 27, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 29, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 34, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 37, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 38, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 39, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 41, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 28, 42, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 31, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 35, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 30, 40, NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 32, 33, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 5, 32, 36, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 6, 7, NULL, NULL);
Query OK, 1 row affected (0.06 sec)

mysql> INSERT INTO `vCategoryTree` (`level1`, `level2`, `level3`, `level4`, `level5`) VALUES (0, 6, 8, NULL, NULL);
Query OK, 1 row affected (0.07 sec)

mysql> select * from vCategoryTree;
+--------+--------+--------+--------+--------+
| level1 | level2 | level3 | level4 | level5 |
+--------+--------+--------+--------+--------+
|      0 |      2 |     43 |     44 |   NULL |
|      0 |      2 |     43 |     45 |   NULL |
|      0 |      2 |     43 |     46 |   NULL |
|      0 |      2 |     47 |     48 |   NULL |
|      0 |      2 |     47 |     49 |   NULL |
|      0 |      2 |     47 |     50 |   NULL |
|      0 |      2 |     47 |     51 |   NULL |
|      0 |      2 |     47 |     52 |   NULL |
|      0 |      2 |     47 |     53 |   NULL |
|      0 |      2 |     47 |     54 |   NULL |
|      0 |      2 |     47 |     55 |   NULL |
|      0 |      2 |     47 |     56 |   NULL |
|      0 |      2 |     47 |     57 |   NULL |
|      0 |      2 |     47 |     58 |   NULL |
|      0 |      2 |     47 |     59 |   NULL |
|      0 |      2 |     47 |     60 |   NULL |
|      0 |      2 |     61 |     62 |   NULL |
|      0 |      2 |     61 |     63 |   NULL |
|      0 |      2 |     61 |     64 |   NULL |
|      0 |      2 |     61 |     65 |   NULL |
|      0 |      2 |     61 |     66 |   NULL |
|      0 |      2 |     61 |     67 |   NULL |
|      0 |      2 |     61 |     68 |   NULL |
|      0 |      2 |     61 |     69 |   NULL |
|      0 |      2 |     61 |     70 |   NULL |
|      0 |      4 |      9 |     10 |   NULL |
|      0 |      4 |      9 |     25 |   NULL |
|      0 |      4 |      9 |     26 |   NULL |
|      0 |      4 |     11 |     12 |   NULL |
|      0 |      4 |     11 |     13 |   NULL |
|      0 |      4 |     14 |     15 |   NULL |
|      0 |      4 |     14 |     16 |   NULL |
|      0 |      4 |     14 |     17 |   NULL |
|      0 |      4 |     14 |     18 |   NULL |
|      0 |      4 |     14 |     19 |   NULL |
|      0 |      4 |     14 |     20 |   NULL |
|      0 |      4 |     14 |     21 |   NULL |
|      0 |      4 |     14 |     22 |   NULL |
|      0 |      4 |     14 |     23 |   NULL |
|      0 |      4 |     14 |     24 |   NULL |
|      0 |      4 |     14 |     27 |   NULL |
|      0 |      5 |     28 |     29 |   NULL |
|      0 |      5 |     28 |     34 |   NULL |
|      0 |      5 |     28 |     37 |   NULL |
|      0 |      5 |     28 |     38 |   NULL |
|      0 |      5 |     28 |     39 |   NULL |
|      0 |      5 |     28 |     41 |   NULL |
|      0 |      5 |     28 |     42 |   NULL |
|      0 |      5 |     30 |     31 |   NULL |
|      0 |      5 |     30 |     35 |   NULL |
|      0 |      5 |     30 |     40 |   NULL |
|      0 |      5 |     32 |     33 |   NULL |
|      0 |      5 |     32 |     36 |   NULL |
|      0 |      6 |      7 |   NULL |   NULL |
|      0 |      6 |      8 |   NULL |   NULL |
+--------+--------+--------+--------+--------+
55 rows in set (0.00 sec)

mysql>

Now here the very, very ugly query you need

SELECT level,parent,IFNULL(child,'Leaf') child FROM (
    SELECT DISTINCT level1 parent,level2 child,1 level
    FROM vCategoryTree WHERE level1 IS NOT NULL OR level2 IS NOT NULL UNION
    SELECT DISTINCT level2       ,level3      ,2
    FROM vCategoryTree WHERE level2 IS NOT NULL OR level3 IS NOT NULL UNION
    SELECT DISTINCT level3       ,level4      ,3
    FROM vCategoryTree WHERE level3 IS NOT NULL OR level4 IS NOT NULL UNION
    SELECT DISTINCT level4       ,level5      ,4
    FROM vCategoryTree WHERE level4 IS NOT NULL OR level5 IS NOT NULL
) A order by level,parent,IFNULL(child,999999999);

It will present each parent and child and the level of the parent.

Each row whose child is NULL is a leaf in the tree

Now here two stored procedures that I hope gives you basically a treelike display you are seeking

The first stored procedure creates a table called DisplayTree and puts the parent of your choice

DELIMITER $$

DROP PROCEDURE IF EXISTS `DisplayTree` $$
CREATE DEFINER=`lwdba`@`127.0.0.1` PROCEDURE `DisplayTree`(given_parent INT UNSIGNED)
BEGIN

    DROP TABLE IF EXISTS DisplayTree;
    CREATE TABLE DisplayTree
    (
        id INT NOT NULL AUTO_INCREMENT,
        DIsplayText VARCHAR(1024),
        PRIMARY KEY (id)
    ) ENGINE=MyISAM;

    INSERT INTO DisplayTree (DisplayText) SELECT LPAD(given_parent,4,' ');
    CALL LoadDisplayTree(given_parent,1);

    SELECT DisplayText FROM DisplayTree;

END $$

DELIMITER ;

The second stored procedure is a recursive one that populates the temp table DisplayTree

DELIMITER $$

DROP PROCEDURE IF EXISTS `LoadDisplayTree` $$
CREATE DEFINER=`lwdba`@`127.0.0.1` PROCEDURE `LoadDisplayTree`(given_parent INT UNSIGNED,given_level INT UNSIGNED)
TheStoredProcedure:BEGIN

    DECLARE children VARCHAR(255);
    DECLARE howmanykids,ndx,ps1,ps2,next_child INT;

    SET children = '';

    SELECT COUNT(1) INTO howmanykids FROM
    (
        SELECT level,parent,child FROM (
        SELECT DISTINCT level1 parent,level2 child,1 level
        FROM vCategoryTree WHERE level1 IS NOT NULL OR level2 IS NOT NULL UNION
        SELECT DISTINCT level2       ,level3      ,2
        FROM vCategoryTree WHERE level2 IS NOT NULL OR level3 IS NOT NULL UNION
        SELECT DISTINCT level3       ,level4      ,3
        FROM vCategoryTree WHERE level3 IS NOT NULL OR level4 IS NOT NULL UNION
        SELECT DISTINCT level4       ,level5      ,4
        FROM vCategoryTree WHERE level4 IS NOT NULL OR level5 IS NOT NULL
        ) AA order by parent,level,IFNULL(child,999999999)
    ) A WHERE parent = given_parent AND child IS NOT NULL;

    IF howmanykids = 0 THEN
        LEAVE TheStoredProcedure;
    END IF;

    SELECT CONCAT(GROUP_CONCAT(child),',') INTO children FROM
    (
        SELECT level,parent,child FROM (
        SELECT DISTINCT level1 parent,level2 child,1 level
        FROM vCategoryTree WHERE level1 IS NOT NULL OR level2 IS NOT NULL UNION
        SELECT DISTINCT level2       ,level3      ,2
        FROM vCategoryTree WHERE level2 IS NOT NULL OR level3 IS NOT NULL UNION
        SELECT DISTINCT level3       ,level4      ,3
        FROM vCategoryTree WHERE level3 IS NOT NULL OR level4 IS NOT NULL UNION
        SELECT DISTINCT level4       ,level5      ,4
        FROM vCategoryTree WHERE level4 IS NOT NULL OR level5 IS NOT NULL
        ) AA order by parent,level,IFNULL(child,999999999)
    ) A WHERE parent = given_parent AND child IS NOT NULL;

    SET ndx = 0;
    SET ps2 = 0;
    WHILE ndx < howmanykids DO
        SET ps1 = ps2 + 1;
        SET ps2 = ps2 + 1;
        WHILE SUBSTR(children,ps2,1) <> ',' DO
            SET ps2 = ps2 + 1;
        END WHILE;
        SET next_child = SUBSTR(children,ps1,ps2 - ps1);
        INSERT INTO DisplayTree (DisplayText)
        SELECT REPLACE(CONCAT(LPAD('X',(given_level * 8),'X'),LPAD(next_child,4,'X')),'X',' ');
        CALL LoadDisplayTree(next_child,given_level + 1);
        SET ndx = ndx + 1;
    END WHILE;

END $$

DELIMITER ;
Give it a Try !!!

Let’s display starting with parent_id 0 :

mysql> call displaytree(0);
+------------------------------+
| DisplayText                  |
+------------------------------+
|    0                         |
|            2                 |
|                   43         |
|                           44 |
|                           45 |
|                           46 |
|                   47         |
|                           48 |
|                           49 |
|                           50 |
|                           51 |
|                           52 |
|                           53 |
|                           54 |
|                           55 |
|                           56 |
|                           57 |
|                           58 |
|                           59 |
|                           60 |
|                   61         |
|                           62 |
|                           63 |
|                           64 |
|                           65 |
|                           66 |
|                           67 |
|                           68 |
|                           69 |
|                           70 |
|            4                 |
|                    9         |
|                           10 |
|                           25 |
|                           26 |
|                   11         |
|                           12 |
|                           13 |
|                   14         |
|                           15 |
|                           16 |
|                           17 |
|                           18 |
|                           19 |
|                           20 |
|                           21 |
|                           22 |
|                           23 |
|                           24 |
|                           27 |
|            5                 |
|                   28         |
|                           29 |
|                           34 |
|                           37 |
|                           38 |
|                           39 |
|                           41 |
|                           42 |
|                   30         |
|                           31 |
|                           35 |
|                           40 |
|                   32         |
|                           33 |
|                           36 |
|            6                 |
|                    7         |
|                    8         |
+------------------------------+
69 rows in set (0.20 sec)

Query OK, 0 rows affected (0.25 sec)

mysql>

You do not have to start with parent_id 0. Let’s try parent_id 4 :

mysql> call displaytree(4);
+----------------------+
| DisplayText          |
+----------------------+
|    4                 |
|            9         |
|                   10 |
|                   25 |
|                   26 |
|           11         |
|                   12 |
|                   13 |
|           14         |
|                   15 |
|                   16 |
|                   17 |
|                   18 |
|                   19 |
|                   20 |
|                   21 |
|                   22 |
|                   23 |
|                   24 |
|                   27 |
+----------------------+
20 rows in set (0.11 sec)

Query OK, 0 rows affected (0.12 sec)

mysql>

CAVEAT

Since recursion is involved, run this

mysql> set max_sp_recursion_depth = 64;
Query OK, 0 rows affected (0.00 sec)

mysql>

before calling DisplayTree

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