php结合mysql查询无限下级树输出

树输出

function get_array($user_id,$top=0){
global $mysql,$_G;
   $sql = "select  user_id as name from `{spreads_users}`   where p1.spreads_userid='{$user_id}'";
$rows= $mysql->db_fetch_arrays($sql);
    if($top==1){
    $arr[0]['name']=$user_id;
    $arr[0]['children']=array();
    }
    $top=$top+1;
foreach ($rows as $key=>$value)
 {
            $r = get_array($value['name']); //调用函数，传入参数，继续查询下级   
            $arr[0]['children'][$key]['name']= $value['username']; //组合数组
            if(is_array($r)){
            $arr[0]['children'][$key]['children']= $r[0]['children'];
            }
          
           $i++;
        }
       
       
        return $arr;
    }
$list = get_array("1000",1); //调用函数  1000是顶级ID
echo 'var data='.json_encode($list);
 
这个是输出 Array 然后转让为 json 本教程由岑溪网站开发提供! 实测

例子

表结构：id字段为分类标识，name字段为分类名，father_id字段为所属父分类的id，path字段为分类路径（储存该分类祖先的集合），isdir判断是否是目录（1为是，0为否）。

显示函数：

代码如下://$count为分类等级 
sort_list($str,$fatherid,$count) 
{ 
$rs = $this->sql->re_datas("select * from sort where father_id = fatherid"); 
$num = $this->sql->sql_numrows(); 
$i=0; 
$n = 1; 
while(isset($rs[$i])) 
{ 
$name = ""; 
for($n = 1 ; $n < $count ; $n ) 
{ 
$name.="│ "; 
} 
if($i 1==$num) 
{ 
$name.="└─".$rs[$i][name]; 
} 
else 
{ 
$name.="├─".$rs[$i][name]; 
} 
if($rs[$i][isdir]) 
{ 
$str.="".$name.""; 
} 
else 
{ 
$str.=$name"; 
} 
$temp = $count 1; 
$str = $this->sort_list($str,$rs[$i][id],$temp); 
$i ; 
} 
return $str; 
}

其中$this->sql对象为sql操作类对象，re_datas()函数返回查到的数组,sql_numrows()函数返回查询到的数目

调用方法:$sort_list = sort_list($sort_list,0,1);

例子

表:category
id   int   主键,自增
name    varchar    分类名称
pid    int    父类id，默认0

顶级分类的 pid 默认就是0了。当我们想取出某个分类的子分类树的时候，基本思路就是递归，当然，出于效率问题不建议每次递归都查询数据库，通常的做法是先讲所有分类取出来，保存到PHP数组里，再进行处理，最后还可以将结果缓存起来以提高下次请求的效率。

先来构建一个原始数组，这个直接从数据库中拉出来就行：

$categories = array(
    array('id'=>1,'name'=>'电脑','pid'=>0),
    array('id'=>2,'name'=>'手机','pid'=>0),
    array('id'=>3,'name'=>'笔记本','pid'=>1),
    array('id'=>4,'name'=>'台式机','pid'=>1),
    array('id'=>5,'name'=>'智能机','pid'=>2),
    array('id'=>6,'name'=>'功能机','pid'=>2),
    array('id'=>7,'name'=>'超级本','pid'=>3),
    array('id'=>8,'name'=>'游戏本','pid'=>3),
);目标是将它转化为下面这种结构

电脑
—笔记本
——-超级本
——-游戏本
—台式机
手机
—智能机
—功能机

用数组来表示的话，可以增加一个 children 键来存储它的子分类：

array(
    //1对应id，方便直接读取
    1 => array(
        'id'=>1,
        'name'=>'电脑',
        'pid'=>0,
        children=>array(
            &array(
                'id'=>3,
                'name'=>'笔记本',
                'pid'=>1,
                'children'=>array(
                    //此处省略
                )
            ),
            &array(
                'id'=>4,
                'name'=>'台式机',
                'pid'=>1,
                'children'=>array(
                    //此处省略
                )
            ),
        )
    ),
    //其他分类省略
)处理过程：

$tree = array();
//第一步，将分类id作为数组key,并创建children单元
foreach($categories as $category){
    $tree[$category['id']] = $category;
    $tree[$category['id']]['children'] = array();
}
//第二部，利用引用，将每个分类添加到父类children数组中，这样一次遍历即可形成树形结构。
foreach ($tree as $k=>$item) {
    if ($item['pid'] != 0) {
        $tree[$item['pid']]['children'][] = &$tree[$k];
    }
}
print_r($tree);打印结果如下：

Array
(
    [1] => Array
        (
            [id] => 1
            [name] => 电脑
            [pid] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 3
                            [name] => 笔记本
                            [pid] => 1
                            [children] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 7
                                            [name] => 超级本
                                            [pid] => 3
                                            [children] => Array
                                                (
                                                )
                                        )
                                    [1] => Array
                                        (
                                            [id] => 8
                                            [name] => 游戏本
                                            [pid] => 3
                                            [children] => Array
                                                (
                                                )
                                        )
                                )
                        )
                    [1] => Array
                        (
                            [id] => 4
                            [name] => 台式机
                            [pid] => 1
                            [children] => Array
                                (
                                )
                        )
                )
        )
    [2] => Array
        (
            [id] => 2
            [name] => 手机
            [pid] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 5
                            [name] => 智能机
                            [pid] => 2
                            [children] => Array
                                (
                                )
                        )
                    [1] => Array
                        (
                            [id] => 6
                            [name] => 功能机
                            [pid] => 2
                            [children] => Array
                                (
                                )
                        )
                )
        )
    [3] => Array
        (
            [id] => 3
            [name] => 笔记本
            [pid] => 1
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 7
                            [name] => 超级本
                            [pid] => 3
                            [children] => Array
                                (
                                )
                        )
                    [1] => Array
                        (
                            [id] => 8
                            [name] => 游戏本
                            [pid] => 3
                            [children] => Array
                                (
                                )
                        )
                )
        )
    [4] => Array
        (
            [id] => 4
            [name] => 台式机
            [pid] => 1
            [children] => Array
                (
                )
        )
    [5] => Array
        (
            [id] => 5
            [name] => 智能机
            [pid] => 2
            [children] => Array
                (
                )
        )
    [6] => Array
        (
            [id] => 6
            [name] => 功能机
            [pid] => 2
            [children] => Array
                (
                )
        )
    [7] => Array
        (
            [id] => 7
            [name] => 超级本
            [pid] => 3
            [children] => Array
                (
                )
        )
    [8] => Array
        (
            [id] => 8
            [name] => 游戏本
            [pid] => 3
            [children] => Array
                (
                )
        )
)优点：关系清楚，修改上下级关系简单。

缺点：使用PHP处理，如果分类数量庞大，效率也会降低。