php无限分类根据顶类获取所有子类

 首先建立分类信息表：

CREATE TABLE IF NOT EXISTS `category` (
  `categoryId` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `parentId` smallint(5) unsigned NOT NULL DEFAULT '0',
  `categoryName` varchar(50) NOT NULL,
  PRIMARY KEY (`categoryId`)
)  ;

插入若干数据： 

CREATE TABLE IF NOT EXISTS `category` (
  `categoryId` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `parentId` smallint(5) unsigned NOT NULL DEFAULT '0',
  `categoryName` varchar(50) NOT NULL,
  PRIMARY KEY (`categoryId`)
)  ;
 
INSERT INTO `category` (`categoryId`, `parentId`, `categoryName`) VALUES
(1, 0, 'php'),
(2, 0, 'java'),
(3, 0, 'c/c++'),
(4, 1, 'php基础'),
(5, 1, 'php开源资料'),
(6, 1, 'php框架'),
(7, 2, 'java Se'),
(8, 2, 'java EE'),
(9, 2, 'java Me'),
(10, 3, 'c/c++基础编程'),
(11, 3, 'c/c++系统开发'),
(12, 3, 'c嵌入式编程'),
(13, 3, 'c++应用开发'),
(14, 13, 'c++桌面应用开发'),
(15, 13, 'c++游戏开发');

下面是php代码： 

*/
 
//获取某分类的直接子分类
function getSons($categorys,$catId=0){
	$sons=array();
	foreach($categorys as $item){
		if($item['parentId']==$catId)
			$sons[]=$item;
	}
	return $sons;
}
 
//获取某个分类的所有子分类
function getSubs($categorys,$catId=0,$level=1){
	$subs=array();
	foreach($categorys as $item){
		if($item['parentId']==$catId){
			$item['level']=$level;
			$subs[]=$item;
			$subs=array_merge($subs,getSubs($categorys,$item['categoryId'],$level+1));
			
		}
			
	}
	return $subs;
}
 
//获取某个分类的所有父分类
//方法一，递归
function getParents($categorys,$catId){
	$tree=array();
	foreach($categorys as $item){
		if($item['categoryId']==$catId){
			if($item['parentId']>0)
				$tree=array_merge($tree,getParents($categorys,$item['parentId']));
			$tree[]=$item;	
			break;	
		}
	}
	return $tree;
}
 
//方法二,迭代
function getParents2($categorys,$catId){
	$tree=array();
	while($catId != 0){
		foreach($categorys as $item){
			if($item['categoryId']==$catId){
				$tree[]=$item;
				$catId=$item['parentId'];
				break;	
			}
		}
	}
	return $tree;
}
 
 
//测试 部分
$pdo=new PDO('mysql:host=localhost;dbname=test','root','8888');
$stmt=$pdo->query("select * from category order by categoryId");
$categorys=$stmt->fetchAll(PDO::FETCH_ASSOC);
 
$result=getSons($categorys,1);
foreach($result as $item)
	echo $item['categoryName'].'<br>';
echo '<hr>';
 
$result=getSubs($categorys,0);
foreach($result as $item)
	echo str_repeat('  ',$item['level']).$item['categoryName'].'<br>';
echo '<hr>';
 
$result=getParents($categorys,7);
foreach($result as $item)
	echo $item['categoryName'].' >> ';
echo '<hr>';
 
$result=getParents2($categorys,15);
foreach($result as $item)
	echo $item['categoryName'].' >> ';
?>

$category_list = array(
	array('id'=>1, 'name'=>'1级分类 1', 'pid'=>0),
	array('id'=>2, 'name'=>'1级分类 2', 'pid'=>0),
	array('id'=>3, 'name'=>'1级分类 3', 'pid'=>0),
	array('id'=>4, 'name'=>'2级分类 1', 'pid'=>1),
	array('id'=>5, 'name'=>'2级分类 2', 'pid'=>2),
	array('id'=>6, 'name'=>'3级分类 1', 'pid'=>4),
	array('id'=>7, 'name'=>'3级分类 2', 'pid'=>5),
	array('id'=>8, 'name'=>'4级分类 1', 'pid'=>6),
	array('id'=>9, 'name'=>'3级分类 2', 'pid'=>5),
 
);
$son_list = getSubs($category_list, 2);
 
function getSubs($categorys,$catId=0,$level=1){  
    $subs=array();  
    foreach($categorys as $item){  
        if($item['pid']==$catId){  
            $item['level']=$level;  
            $subs[]=$item;  
            $subs=array_merge($subs,getSubs($categorys,$item['id'],$level+1));  
            
        }  
              
    }  
	
	/*
	print_r结果：先进后出（2-》5-》7、9）
	array_merge(array(5), array(7,9))		 4
	getSubs()得到array(7,9)					 3
		array_merge(array(7), array())       1
		array_merge(array(7,9), array())     2	
	*/
	print_r($subs);   
    return $subs;  
}  

例子：

$category_list = array(
	array('id'=>1, 'name'=>'1级分类 1', 'pid'=>0),
	array('id'=>2, 'name'=>'1级分类 2', 'pid'=>0),
	array('id'=>3, 'name'=>'1级分类 3', 'pid'=>0),
	array('id'=>4, 'name'=>'2级分类 1', 'pid'=>1),
	array('id'=>5, 'name'=>'2级分类 2', 'pid'=>2),
	array('id'=>6, 'name'=>'3级分类 1', 'pid'=>4),
	array('id'=>7, 'name'=>'3级分类 2', 'pid'=>5),
	array('id'=>8, 'name'=>'4级分类 1', 'pid'=>6),
	array('id'=>9, 'name'=>'3级分类 2', 'pid'=>5),
 
);
 
$a = getSonx(1, $category_list);
//print_r($a);exit;
function getSonx($id, $data){
	$returnData = array();
	foreach($data as $k=>$v){
		if($v['pid'] == $id){
			$returnData[]		= $v;
			$a	= getSonx($v['id'], $data);
			if($a){
				print_r($a);
				$returnData	= array_merge($returnData, $a);
			}
			//从最底层数据，向上合并。
			//for pid=5层，id:7,9是最底层了，getSonx()返回的是2个空array因为(没有子类)
			//结果：$returnData = array(7,9); 即$returnData[];
			//for pid=2层，id:5  合并刚才的7,9  $returnData = array(7,9);
			//结果：$returnData = array(5,7,9);
		}
	}
	
	return $returnData;
}
 
exit;

下面是运行的结果：

from:https://blog.csdn.net/kankan231/article/details/8462349