MYSQL父子同表； PHP 将子代嵌套在父代中作为多维数组

Posted 2023-02-24

【中文标题】MYSQL父子同表； PHP 将子代嵌套在父代中作为多维数组

【英文标题】：MYSQL Parent Child Same Table; PHP Nest Children Within Parents as a Multidimensional-Array

【发布时间】：2012-12-03 00:39:52

【问题描述】：

mysql 返回一个数组，如下所示。我正在使用 column: 'id_parent' 来自引用表以创建层次结构。因此，“id”为 2 的条目可以是任何“id_parent”为 2 的条目的父项，依此类推。

Array 
  (

    [1] => Array
        (
            [id] => 2
            [name] => About
            [id_parent] => NULL
        )

    [2] => Array
        (
            [id] => 4
            [name] => About Child
            [id_parent] => 2
        )

    [3] => Array
        (
            [id] => 5
            [name] => About Child's Child
            [id_parent] => 4
        )
  )

如何将子元素嵌套到其父数组中的数组中

Array
  (

    [1] => Array
        (
            [id] => 2
            [name] => About
            [id_parent] => 
            [children] => Array
                      (
                          [id] => 4
                          [name] => About Child
                          [id_parent] => 2
                          [children] => Array
                                    (
                                        [id] => 5
                                        [name] => About Child's Child
                                        [id_parent] => 4
                                    )
                      )
        )
  )

【参考方案1】：

引用，其优点是顺序无关紧要（子节点可以在其父节点之前）：

 $tree = array('NULL' => array('children' => array()));
 foreach($array as $item)
    if(isset($tree[$item['id']]))
       $tree[$item['id']] = array_merge($tree[$item['id']],$item);
     else 
       $tree[$item['id']] = $item;
    

    $parentid = is_null($item['id_parent']) ? 'NULL' : $item['id_parent'];
    if(!isset($tree[$parentid])) $tree[$parentid] = array('children' => array());
    //this & is where the magic happens: any alteration to $tree[$item['id']
    //  will reflect in the item $tree[$parentid]['children'] as they are the same
    //  variable. For instance, adding a child to $tree[$item['id']]['children]
    //  will be seen in 
    //  $tree[$parentid]['children'][<whatever index $item['id'] has>]['children]
    $tree[$parentid]['children'][] = &$tree[$item['id']];
 
 $result = $tree['NULL']['children'];
 //always unset references
 unset($tree);

【讨论】：

我现在要试试这个。感谢您的快速回复。

第一次看时完全错过了那里的参考资料。很棒的小sn-p！

完美！看到它的工作我很震惊。现在逐行剖析这个漂亮的款待。谢谢！

哇，这是真正的交易。试图通过数组遍历数组映射数组减少来做到这一点，我变得太复杂了。这很简单，很有效，谢谢。