利用数据库表实现无限级分类

 1,
		'name' => 'java',
		'pid' => 0,
		'path' => '0'
	),
	array(
		'id' => 2,
		'name' => 'php',
		'pid' => 0,
		'path' => '0'
	),
	array(
		'id' => 3,
		'name' => 'java基础',
		'pid' => 1,
		'path' => '0-1'
	),
	array(
		'id' => 4,
		'name' => 'php基础',
		'pid' => 2,
		'path' => '0-2'
	),
	array(
		'id' => 5,
		'name' => 'java数组',
		'pid' => 3,
		'path' => '0-1-3'
	),
	array(
		'id' => 6,
		'name' => 'php变量',
		'pid' => 4,
		'path' => '0-2-4'
	),
);

/*
echo '
';
print_r($data);
echo '
';
*/

//设置分级字段
foreach($data as &$row) {
	//计算-出现的个数
	$num = substr_count($row['path'],'-');
	if($row['pid'] > 0) {
		//设置前缀字符  |--
		$rep = '|'.str_repeat('--',$num);
	}else {
		$rep = '';	
	}
	
	//在数组里设置一个新的字段，存储分级的结果
	$row['tree'] = $rep.$row['name'];
}

//取得分级的排序数组
/*
	思路：用path+id 取得一个数值。利用此数值来排序
	Array ( 
			[0] => 0-1 
			[1] => 0-2 
			[2] => 0-1-3 
			[3] => 0-2-4 
			[4] => 0-1-3-5 
			[5] => 0-2-4-6 )
*/
foreach($data as $row2) {
	$arr[] = $row2['path'].'-'.$row2['id'];
}


//排序
array_multisort($arr, $data);//第二个数组根据对应第一个数组后也进行排序。 

/*
	$arr排序后的结果:
	Array ( [0] => 0-1 
			[1] => 0-1-3 
			[2] => 0-1-3-5
			[3] => 0-2 
			[4] => 0-2-4 
			[5] => 0-2-4-6 )
	
*/

//取得排序后的分级结果
foreach($data as $row3) {
	echo $row3['tree'].'
';
}

/*
java
|--java基础
|----java数组
php
|--php基础
|----php变量
*/