Php + mysql does not require recursive implementation of unlimited classification instances (non-recursive), mysql recursion _ PHP Tutorial

Php + mysql does not require recursive implementation of unlimited classification instances (non-recursive), mysql recursion. Php + mysql does not require recursive implementation of infinite-level classification instances (non-recursive). mysql recursion requires the implementation of infinite-level classification. recursion is generally the first and easiest to think, however, recursion is generally considered to take up an infinite number of classification instances (non-recursive) that are not implemented recursively by php + mysql, and mysql recursion.

Recursion is generally the first and easiest way to achieve an infinite classification, but recursion is generally considered a resource-consuming method. Therefore, many systems do not consider 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!

Php recursion problem, want to display the data according to the Infinitus classification style

First, decode the json into an array. use the json_decode function to add the second parameter. Otherwise, it will return an object. The next step is recursive. This is the simplest recursion. you only need to traverse them one by one.
The complete code is as follows:
$ Data = json_decode ($ str, true); $ options = getChildren ($ data); function getChildren ($ parent, $ deep = 0) {foreach ($ parent as $ row) {$ data [] = array ("id" => $ row ['id'], "name" => $ row ['name'], "pid" => $ row ['parentid'], 'Deep '=> $ deep); if ($ row ['childs']) {$ data = array_merge ($ data, getChildren ($ row ['Childs '], $ deep + 1) ;}return $ data ;}?> </Option> </Select>The above code has passed the test as follows:Php recursion (Infinitus classification)Foreach itself is equivalent to judgment. when the $ arr array is not empty, foreach will traverse and recursively access the child node, but for the leaf node, the $ arr array is empty, it will not be foreach at all, and return directly at this time. Understand?Recursive (non-recursive): mysql recursion requires an infinite number of classes. recursion is generally the first and easiest to think of, but recursion is generally considered to occupy...