PHP-将数据库数据转化成php树形结构数组的高效算法

Question

数据库结构及数据如下所示：
id pid name
1 0 11111
2 1 22222
3 0 33333
4 3 44444
5 4 55555
6 1 66666

想输入如下的php数组：

array(
    array(
        'id'=>1,
        'name'=>'11111',
        'children'=>array(           
            array(
                'id'=>2,
                'name'=>'22222',
                'children'=>array()
            ),
            array(
                'id'=>6,
                'name'=>'66666',
                'children'=>array()
            )
        )
    ),
    array(
        'id'=>3,
        'name'=>'33333',
        'children'=>array(
            'id'=>4,
            'name'=>'44444',
            'children'=>array(
                array(
                    'id'=>5,
                    'name'=>'55555',
                    'children'=>array()
                )

            )   
        )
    ),
)

Answer 1

分享一个自己收藏的非递归方法：

 /**
* 生成树数组
* @param $data 从数据库出来select出来的数数组
* @return [{"id":1,"name":"Folder1", "children":[{"id":1,"name":"File1"}] }]
* */
function treeArray($data)
{
$result = array();
//定义索引数组，用于记录节点在目标数组的位置，类似指针
$p = array();

foreach($data as $val)
{
if($val['pid'] == 0)
{
$i = count($result);
$result[$i] = isset($p[$val['id']])? array_merge($val,$p[$val['id']]) : $val;
$p[$val['id']] = & $result[$i];
} else {
$i = count($p[$val['pid']]['children']);
$p[$val['pid']]['children'][$i] = $val;
$p[$val['id']] = & $p[$val['pid']]['children'][$i];
}
}

return $result;
}

Answer 2

刚写了一个，主要利用递归：

function create_tree($arr,$pid=0) {
$ret = array();
foreach($arr as $k => $v) {
if($v['pid'] == $pid) {
$tmp = $arr[$k];unset($arr[$k]);
$tmp['children'] = create_tree($arr,$v['id']);
$ret[] = $tmp;
}
}
return $ret;
}

测试：

$arr = array(
array('id'=>1,'pid'=>'0','name'=>'11111'),
array('id'=>2,'pid'=>'1','name'=>'22222'),
array('id'=>3,'pid'=>'0','name'=>'33333'),
array('id'=>4,'pid'=>'3','name'=>'44444'),
array('id'=>5,'pid'=>'4','name'=>'55555'),
array('id'=>6,'pid'=>'1','name'=>'66666')
);

echo "<pre>";
print_r(create_tree($arr));