6

我有这样的表结构

mysql> SELECT id, name, parent_id FROM categories;
+-------+------------+-----------+
| id    | name       | parent_id |
+-------+------------+-----------+
| 15790 | Test       |         0 |
| 15791 | Test2      |         0 |
| 16079 | Subtest    |     15790 |
| 16080 | Subtest 2  |     15790 |
| 16081 | Subsubtest |     16079 |
+-------+------------+-----------+

现在我想为每个孩子和兄弟姐妹查找父母，并以正确的顺序将其返回以进行删除。

所以我在这种情况下的输出是：

Array
(
  16081,
  16080,
  16079,
  15791,
  15790
)

我不能仅通过反转父 ID 来删除，因为这应该是可靠的走回树。

此外，我无法/不允许更改表格的结构。所以建立一种索引是必要的。

4

5 回答 5

6

假设您无权访问TRUNCATE, SET（所以您可以这样做SET FOREIGN_KEY_CHECKS=0;）、ALTER等，并且绝对必须使用脚本：

由于问题被标记为php，这应该可以解决问题：

function reversetree($src_arr, $currentid = 0)
{
    $cats = array();
    foreach($src_arr as $id => $parent)
    {   
        if($parent == $currentid)
        {
            $cats[] = $id;
            $cats = array_merge($cats, reversetree($src_arr, $id));
        }
    }
    return !$currentid ? array_reverse($cats) : $cats;
}

$rs = array();
foreach($pdo->query('SELECT id, parent_id FROM categories') as $row)
    $rs[$row['id']] = $row['parent_id'];

$stmt = $pdo->prepare('DELETE FROM categories WHERE id = ?');

$pdo->beginTransaction();
foreach(reversetree($rs) as $v)
    $stmt->execute(array($v));
$pdo->commit();
于 2012-06-26T05:25:47.230 回答
3

我不明白为什么您需要按特定顺序使用 ID。您可以通过事务删除它们，它们将同时被删除。

DELETE FROM categories WHERE ID IN (15790,15791,16079,16080,16081);
于 2012-06-26T00:36:31.943 回答
1 
<?php

// housekeeping
$pdo = new PDO($dsn, $user, $password);
$select = $pdo->prepare(
    "SELECT parent.id AS parent_id, child.id AS child_id
    FROM categories AS parent
    JOIN categories AS child ON parent.id = child.parent_id
    WHERE parent.id = ?"
);
$delete = $pdo->prepare('DELETE FROM categories WHERE id = ?');

// deletes $node_id, deletes its children first if required
function delete_node($node_id){
    $select->execute( array($node_id) );
    $children = $select->fetchAll(PDO::FETCH_NUM);
    if (count($children) !== 0) { // if 0, then the category does not exist, or it has no child
        foreach ($children as $child) { // call delete_node() recursively on each child
            delete_node ($child[1]);
        }
    }
    $delete->execute( array($node_id) ); // then delete this node (or do nothing if $node_id does not exist)
}


// to delete one category and all its sub-categories

delete_node(15790);

// to delete all contents

$allTopLevel = $pdo->exec('SELECT id FROM categories WHERE parent_id = 0')->fetchAll(PDO::FETCH_NUM);
foreach ($allTopLevel as $node) {
    delete_node($node[0]);
}

未经测试，甚至不确定它是否“编译”，但你明白了。确保在调用之前锁定表（或启动事务）delete_node()。

于 2012-06-26T07:11:19.177 回答
1

您可以在 DELETE 上使用 CASCADE 添加 FOREIGN KEY 约束。外键将指向父 id 字段上的同一个表。

当您删除父级时，所有子级（无论哪个级别）都会自动删除。

于 2012-06-22T12:13:29.970 回答
0

抱歉，我帮不上什么忙，因为 SQL 不是我的菜。但也许有人可以将java伪代码转移到解决方案中

delete(table.getFirstRow().get(id));

delete(id_a){
    for(data_set : table)
        if(data_set.get(parent_id) == id_a)delete(data_set.get(id));
    }
    table.remove(id_a);
}

编辑：没有关于元素的迭代？所以像这样的东西？

delete(list){
    if(list.size() == 0)return;
    idList = list.getAll(id);
    plist = table.getAllWhichEquals(parent_id, idList);
    delete(plist);
    table.remove(idList);
}

啊，算了，我不是同时删除，只是试一试^^

于 2012-06-26T04:07:56.227 回答