具有单个查询的递归类别? [英] Recursive categories with a single query?
问题描述
我有一个包含文章和栏目的网站,每个部分都可以有一个父部分,只要他们喜欢例如:
I have a website with articles and sections, each sections can have a parent section, as much as they like for example:
subject 1
-subject 2
--subject 3
-subject 4
--subject 5
--subject 6
---subject 7
subject 8
subject 9
等等.
现在,我想递归地获取它们,通过 php 和 mysql 最有效的方法是什么?
Now, i want to fetch them recursively, what is the most efficient way to do it via php and mysql?
先进的 Tnx.
推荐答案
如果树不是太大,您可以使用一些巧妙的引用在 PHP 中简单地构建树.
If the tree isn't too large, you can simply build the tree in PHP using some clever references.
$nodeList = array();
$tree = array();
$query = mysql_query("SELECT category_id, name, parent FROM categories ORDER BY parent");
while($row = mysql_fetch_assoc($query)){
$nodeList[$row['category_id']] = array_merge($row, array('children' => array()));
}
mysql_free_result($query);
foreach ($nodeList as $nodeId => &$node) {
if (!$node['parent'] || !array_key_exists($node['parent'], $nodeList)) {
$tree[] = &$node;
} else {
$nodeList[$node['parent']]['children'][] = &$node;
}
}
unset($node);
unset($nodeList);
这将为您提供 $tree
中的树结构,以及相应 children
-slot 中的子项.
This will give you the tree structure in $tree
with the children in the respective children
-slot.
我们已经用相当大的树(>> 1000 个项目)完成了这项工作,它非常稳定,而且比在 MySQL 中执行递归查询要快得多.
We've done this with fairly large trees ( >> 1000 items) and it's very stable and a lot faster than doing recursive queries in MySQL.
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