带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版块的网站， 每个部分可以根据需要设置一个父部分 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.

现在，我想递归地获取它们，最有效的方法是通过php和mysql吗?

Now, i want to fetch them recursively, what is the most efficient way to do it via php and mysql?

高级Tnx.

推荐答案

如果树不是太大，则可以使用一些聪明的引用在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，其子级分别位于children插槽中.

This will give you the tree structure in $tree with the children in the respective children-slot.

我们已经使用相当大的树(>>有1000多个树)完成了此操作，它非常稳定，并且比在MySQL中进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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