将数据库结果转换为数组

Question

我刚刚为组织此表中第70页上显示的查询层次结构数据的“关闭表”方法做了“更新/添加/删除”部分：http ://www.slideshare.net/billkarwin/sql-antipatterns-
strike -背部

我的数据库如下所示：

表类别：

ID         Name
1          Top value
2          Sub value1

表类别树：

child     parent     level
1          1         0
2          2         0  
2          1         1

但是，从单个查询获取整棵树作为多维数组时，我遇到了一个问题。

这是我想回来的东西：

 array (

 'topvalue' = array (
                     'Subvalue',
                     'Subvalue2',
                     'Subvalue3)
                     );

 );

更新：
找到了此链接，但是我仍然很难将其转换为数组：http : //karwin.blogspot.com/2010/03/rendering-
trees-with-closure-tables.html

Update2： 我现在可以为每个类别添加深度，如果有帮助的话。

Answer 1

好的，我编写了PHP类来扩展Zend Framework DB表，行和行集类。无论如何，我一直在开发它，因为我在PHP
Tek-X
上谈论了两周有关分层数据模型的内容。

我不想将我所有的代码发布到Stack Overflow，因为如果这样做，它们将隐式地获得知识共享许可。 更新： 我将代码提交给Zend
Framework
Extras孵化器，在幻灯片共享中，我的演示文稿是带有SQL和PHP的分层数据模型。

我将用伪代码描述解决方案。我使用的是动物学分类学作为测试数据，可从ITIS.gov下载。该表是longnames：

CREATE TABLE `longnames` (
  `tsn` int(11) NOT NULL,
  `completename` varchar(164) NOT NULL,
  PRIMARY KEY (`tsn`),
  KEY `tsn` (`tsn`,`completename`)
)

我为分类法层次结构中的路径创建了一个 封闭表 ：

CREATE TABLE `closure` (
  `a` int(11) NOT NULL DEFAULT '0',  -- ancestor
  `d` int(11) NOT NULL DEFAULT '0',  -- descendant
  `l` tinyint(3) unsigned NOT NULL,  -- levels between a and d
  PRIMARY KEY (`a`,`d`),
  CONSTRAINT `closure_ibfk_1` FOREIGN KEY (`a`) REFERENCES `longnames` (`tsn`),
  CONSTRAINT `closure_ibfk_2` FOREIGN KEY (`d`) REFERENCES `longnames` (`tsn`)
)

给定一个节点的主键，您可以通过以下方式获取其所有后代：

SELECT d.*, p.a AS `_parent`
FROM longnames AS a
JOIN closure AS c ON (c.a = a.tsn)
JOIN longnames AS d ON (c.d = d.tsn)
LEFT OUTER JOIN closure AS p ON (p.d = d.tsn AND p.l = 1)
WHERE a.tsn = ? AND c.l <= ?
ORDER BY c.l;

联接要closure AS p包括每个节点的父ID。

该查询很好地利用了索引：

+----+-------------+-------+--------+---------------+---------+---------+----------+------+-----------------------------+
| id | select_type | table | type   | possible_keys | key     | key_len | ref      | rows | Extra                       |
+----+-------------+-------+--------+---------------+---------+---------+----------+------+-----------------------------+
|  1 | SIMPLE      | a     | const  | PRIMARY,tsn   | PRIMARY | 4       | const    |    1 | Using index; Using filesort |
|  1 | SIMPLE      | c     | ref    | PRIMARY,d     | PRIMARY | 4       | const    | 5346 | Using where                 |
|  1 | SIMPLE      | d     | eq_ref | PRIMARY,tsn   | PRIMARY | 4       | itis.c.d |    1 |                             |
|  1 | SIMPLE      | p     | ref    | d             | d       | 4       | itis.c.d |    3 |                             |
+----+-------------+-------+--------+---------------+---------+---------+----------+------+-----------------------------+

鉴于我有490,032行longnames和4,299,883行closure，它的运行时间相当不错：

+--------------------+----------+
| Status             | Duration |
+--------------------+----------+
| starting           | 0.000257 |
| Opening tables     | 0.000028 |
| System lock        | 0.000009 |
| Table lock         | 0.000013 |
| init               | 0.000048 |
| optimizing         | 0.000032 |
| statistics         | 0.000142 |
| preparing          | 0.000048 |
| executing          | 0.000008 |
| Sorting result     | 0.034102 |
| Sending data       | 0.001300 |
| end                | 0.000018 |
| query end          | 0.000005 |
| freeing items      | 0.012191 |
| logging slow query | 0.000008 |
| cleaning up        | 0.000007 |
+--------------------+----------+

现在，我对上述SQL查询的结果进行后处理，根据层次结构（伪代码）将行分类为子集：

while ($rowData = fetch()) {
  $row = new RowObject($rowData);
  $nodes[$row["tsn"]] = $row;
  if (array_key_exists($row["_parent"], $nodes)) {
    $nodes[$row["_parent"]]->addChildRow($row);
  } else {
    $top = $row;
  }
}
return $top;

我还为“行”和“行集”定义类。行集基本上是行的数组。行包含行数据的关联数组，还包含其子级的行集。叶节点的子行集为空。

行和行集还定义了称为的方法toArrayDeep()，这些方法以纯数组的形式递归地转储其数据内容。

然后，我可以像这样一起使用整个系统：

// Get an instance of the taxonomy table data gateway 
$tax = new Taxonomy();

// query tree starting at Rodentia (id 180130), to a depth of 2
$tree = $tax->fetchTree(180130, 2);

// dump out the array
var_export($tree->toArrayDeep());

输出如下：

array (
  'tsn' => '180130',
  'completename' => 'Rodentia',
  '_parent' => '179925',
  '_children' => 
  array (
    0 => 
    array (
      'tsn' => '584569',
      'completename' => 'Hystricognatha',
      '_parent' => '180130',
      '_children' => 
      array (
        0 => 
        array (
          'tsn' => '552299',
          'completename' => 'Hystricognathi',
          '_parent' => '584569',
        ),
      ),
    ),
    1 => 
    array (
      'tsn' => '180134',
      'completename' => 'Sciuromorpha',
      '_parent' => '180130',
      '_children' => 
      array (
        0 => 
        array (
          'tsn' => '180210',
          'completename' => 'Castoridae',
          '_parent' => '180134',
        ),
        1 => 
        array (
          'tsn' => '180135',
          'completename' => 'Sciuridae',
          '_parent' => '180134',
        ),
        2 => 
        array (
          'tsn' => '180131',
          'completename' => 'Aplodontiidae',
          '_parent' => '180134',
        ),
      ),
    ),
    2 => 
    array (
      'tsn' => '573166',
      'completename' => 'Anomaluromorpha',
      '_parent' => '180130',
      '_children' => 
      array (
        0 => 
        array (
          'tsn' => '573168',
          'completename' => 'Anomaluridae',
          '_parent' => '573166',
        ),
        1 => 
        array (
          'tsn' => '573169',
          'completename' => 'Pedetidae',
          '_parent' => '573166',
        ),
      ),
    ),
    3 => 
    array (
      'tsn' => '180273',
      'completename' => 'Myomorpha',
      '_parent' => '180130',
      '_children' => 
      array (
        0 => 
        array (
          'tsn' => '180399',
          'completename' => 'Dipodidae',
          '_parent' => '180273',
        ),
        1 => 
        array (
          'tsn' => '180360',
          'completename' => 'Muridae',
          '_parent' => '180273',
        ),
        2 => 
        array (
          'tsn' => '180231',
          'completename' => 'Heteromyidae',
          '_parent' => '180273',
        ),
        3 => 
        array (
          'tsn' => '180213',
          'completename' => 'Geomyidae',
          '_parent' => '180273',
        ),
        4 => 
        array (
          'tsn' => '584940',
          'completename' => 'Myoxidae',
          '_parent' => '180273',
        ),
      ),
    ),
    4 => 
    array (
      'tsn' => '573167',
      'completename' => 'Sciuravida',
      '_parent' => '180130',
      '_children' => 
      array (
        0 => 
        array (
          'tsn' => '573170',
          'completename' => 'Ctenodactylidae',
          '_parent' => '573167',
        ),
      ),
    ),
  ),
)

关于计算深度-或实际上每个路径的长度，发表您的评论。

假设您刚刚在表中插入了一个包含实际节点的新节点（longnames在上面的示例中），则新节点的ID由LAST_INSERT_ID()MySQL
返回，否则您可以通过某种方式获取它。

INSERT INTO Closure (a, d, l)
  SELECT a, LAST_INSERT_ID(), l+1 FROM Closure
  WHERE d = 5 -- the intended parent of your new node 
  UNION ALL SELECT LAST_INSERT_ID(), LAST_INSERT_ID(), 0;