Php + mysql unlimited classification instance (non-recursive) _ php instance without Recursion

This article mainly introduces php + mysql unlimited classification instances that do not require recursion, with a focus on non-recursion. For more information, see How to Implement unlimited classification, recursion is generally the first and easiest way to think of, but recursion is generally considered a resource-consuming method, so many systems do not consider using recursion.
This article uses the database design and an SQL statement to implement
The database fields are roughly as follows:

The Code is as follows:

Id
Fid parent category ID
Class_name category name
Path classifier path, which uses id as a node to form a string similar to, 1, 2, 3, and 4.

Assume that the following data is available:

The Code is as follows:

Id fid class_name path
1 0 Category 1, 1,
2 0 Category 2, 2,
3 1 Classification 1-1, 1, 3,
4 1 Classification 1-2, 1, 4,
5 2 categories 2-1, 2, 5,
6 4 categories 1-2-1, 1, 4, 6,

Unlimited operation code:

<? Php $ SQL = "SELECT * FROM tree order by path"; $ result = $ nbs-> Query ($ SQL ); while ($ rows = $ nbs-> fetch_array ($ result) {if (substr_count ($ rows ['path'], ',')> 2) {for ($ I = 0; $ I <(substr_count ($ rows ['path'], ',')-2); $ I ++) echo '';} echo $ rows ['class _ name'].'
';}?> $ Conn = mysql_connect ('localhost', 'root', 'root'); mysql_select_db ('wanggou123 ', $ conn); mysql_query ('set names utf8 '); $ SQL = "select id, concat (catpath, '-', id) as abspath, name from category order by abspath"; $ query = mysql_query ($ SQL ); while ($ row = mysql_fetch_array ($ query) {/*** first Display Method * // * $ space = str_repeat ('', count (explode ('-', $ row ['abspath'])-1); echo $ space. $ row ['name']. ''; * // ** second Display Method */$ space = str_repeat ('--', count (explode ('-', $ row ['abspath']) -1); $ option. = ''. $ space. $ row ['name'].'
';} Echo $ option; exit (); echo''. $ Option .'';

$ Nbs is a database operation class. This method is simple and clear!