PHP 無制限の分類

<?php/** * 此方法由@Tonton 提供 * http://my.oschina.net/u/918697 * @date 2012-12-12  */function genTree5($items) {     foreach ($items as $item)         $items[$item['pid']]['son'][$item['id']] = &$items[$item['id']];     return isset($items[0]['son']) ? $items[0]['son'] : array(); } /** * 将数据格式化成树形结构 * @author Xuefen.Tong * @param array $items * @return array  */function genTree9($items) {    $tree = array(); //格式化好的树    foreach ($items as $item)        if (isset($items[$item['pid']]))            $items[$item['pid']]['son'][] = &$items[$item['id']];        else            $tree[] = &$items[$item['id']];    return $tree;}$items = array(    1 => array('id' => 1, 'pid' => 0, 'name' => '江西省'),    2 => array('id' => 2, 'pid' => 0, 'name' => '黑龙江省'),    3 => array('id' => 3, 'pid' => 1, 'name' => '南昌市'),    4 => array('id' => 4, 'pid' => 2, 'name' => '哈尔滨市'),    5 => array('id' => 5, 'pid' => 2, 'name' => '鸡西市'),    6 => array('id' => 6, 'pid' => 4, 'name' => '香坊区'),    7 => array('id' => 7, 'pid' => 4, 'name' => '南岗区'),    8 => array('id' => 8, 'pid' => 6, 'name' => '和兴路'),    9 => array('id' => 9, 'pid' => 7, 'name' => '西大直街'),    10 => array('id' => 10, 'pid' => 8, 'name' => '东北林业大学'),    11 => array('id' => 11, 'pid' => 9, 'name' => '哈尔滨工业大学'),    12 => array('id' => 12, 'pid' => 8, 'name' => '哈尔滨师范大学'),    13 => array('id' => 13, 'pid' => 1, 'name' => '赣州市'),    14 => array('id' => 14, 'pid' => 13, 'name' => '赣县'),    15 => array('id' => 15, 'pid' => 13, 'name' => '于都县'),    16 => array('id' => 16, 'pid' => 14, 'name' => '茅店镇'),    17 => array('id' => 17, 'pid' => 14, 'name' => '大田乡'),    18 => array('id' => 18, 'pid' => 16, 'name' => '义源村'),    19 => array('id' => 19, 'pid' => 16, 'name' => '上坝村'),);echo "<pre class="brush:php;toolbar:false">";print_r(genTree5($items));print_r(genTree9($items));//后者输出格式，前者类似，只是数组键值不一样，不过不影响数据结构/*Array([0] => Array    (        [id] => 1        [pid] => 0        [name] => 江西省        [son] => Array            (                [0] => Array                    (                        [id] => 3                        [pid] => 1                        [name] => 南昌市                    )                [1] => Array                    (                        [id] => 13                        [pid] => 1                        [name] => 赣州市                        [son] => Array                            (                                [0] => Array                                    (                                        [id] => 14                                        [pid] => 13                                        [name] => 赣县                                        [son] => Array                                            (                                            [0] => Array                                                (                                                    [id] => 16                                                    [pid] => 14                                                    [name] => 茅店镇                                                    [son] => Array                                                        (                                                        [0] => Array                                                            (                                                            [id] => 18                                                            [pid] => 16                                                            [name] => 义源村                                                            )                                                        [1] => Array                                                            (                                                            [id] => 19                                                            [pid] => 16                                                            [name] => 上坝村                                                            )                                                        )                                                )                                            [1] => Array                                                (                                                    [id] => 17                                                    [pid] => 14                                                    [name] => 大田乡                                                )                                            )                                    )                                [1] => Array                                    (                                        [id] => 15                                        [pid] => 13                                        [name] => 于都县                                    )                            )                    )            )    )[1] => Array    (        [id] => 2        [pid] => 0        [name] => 黑龙江省        [son] => Array            (                [0] => Array                    (                        [id] => 4                        [pid] => 2                        [name] => 哈尔滨市                        [son] => Array                            (                            [0] => Array                                (                                    [id] => 6                                    [pid] => 4                                    [name] => 香坊区                                    [son] => Array                                        (                                        [0] => Array                                            (                                                [id] => 8                                                [pid] => 6                                                [name] => 和兴路                                                [son] => Array                                                    (                                                        [0] => Array                                                            (                                                            [id] => 10                                                            [pid] => 8                                                            [name] =>                                                              东北林业大学                                                            )                                                        [1] => Array                                                            (                                                            [id] => 12                                                            [pid] => 8                                                            [name] =>                                                             哈尔滨师范大学                                                            )                                                    )                                            )                                        )                                )                            [1] => Array                                (                                    [id] => 7                                    [pid] => 4                                    [name] => 南岗区                                    [son] => Array                                        (                                        [0] => Array                                            (                                            [id] => 9                                            [pid] => 7                                            [name] => 西大直街                                            [son] => Array                                                (                                                [0] => Array                                                    (                                                    [id] => 11                                                    [pid] => 9                                                    [name] =>                                                      哈尔滨工业大学                                                    )                                                )                                            )                                        )                                )                            )                    )                [1] => Array                    (                        [id] => 5                        [pid] => 2                        [name] => 鸡西市                    )            )    ))*

Array(    [10] => Array        (            [child] => Array                (                    [14] =>                 )        )    [11] =>     [12] =>     [9] => Array        (            [child] => Array                (                    [13] =>                 )        ))

function genTree5($items) {     foreach ($items as $item) {	$items[$item['id']]=$item;//ADD THIS        $items[$item['pid']]['son'][$item['id']] = &$items[$item['id']]; 		}    return isset($items[0]['son']) ? $items[0]['son'] : array(); } 

id 父id   分级   1   0      0，12   1     0，1，23   1     0，1，34   3    0，1，3，4select * from 表  order  by 分级 asc

|--2|----2-1|------2-1-1|--3|----3-1|--4|--1|----1-1