查询无限极分类

 1 /**
 2  * User: finn.lee
 3  * Date: 2016/3/5 14:25
 4  */
 5 $rows = array(
 6     0=>array(
 7         'cat_id' => 1,
 8         'name' => 'dev',
 9         'pid' => 0
10     ),
11     1=>array(
12         'cat_id' => 2,
13         'name' => 'php',
14         'pid' => 1
15     ),
16     2=>array(
17         'cat_id' => 3,
18         'name' => 'smarty',
19         'pid' => 2
20     ),
21     3=>array(
22         'cat_id' => 4,
23         'name' => 'life',
24         'pid' => 0
25     ),
26     4=>array(
27         'cat_id' => 5,
28         'name' => 'pdo',
29         'pid' => 2
30     ),
31     5=>array(
32         'cat_id' => 6,
33         'name' => 'pdo-mysql',
34         'pid' => 5
35     ),
36     6=>array(
37         'cat_id' => 7,
38         'name' => 'java',
39         'pid' => 1
40     )
41 );
42 
43 // 72648
44 // 84072
45 
46 function findChild(&$arr,$id){
47 
48     $childs=array();
49     foreach ($arr as $k => $v){
50         if($v['pid']== $id){
51             $childs[]=$v;
52         }
53     }
54     return $childs;
55 }
56 function build_tree($root_id){
57     global $rows;
58     $childs=findChild($rows,$root_id);
59     if(empty($childs)){
60         return null;
61     }
62     foreach ($childs as $k => $v){
63         $rescurTree=build_tree($v['cat_id']);
64         if( null !=   $rescurTree){
65             $childs[$k]['childs']=$rescurTree;
66         }
67     }
68     return $childs;
69 }
70 
71 
72 $tree=build_tree(0);
73 
74 echo memory_get_usage();
75 
76 print_r($tree);

注: $rows是活的 ， $root_id是活的

来源：http://www.cnblogs.com/finnlee/p/5244932.html