Question

那里，

我的sqlite表中有一些树形结构数据，想要用PHP递归删除它。数据如下所示：

Id    ParentId
0     -1
1     0

功能：

/**
 * Delete a category with all it's subcategories
 * 
 * @param {number} id The id of the category which should be deleted
 * @return {number} The number of categories deleted
 * @throws {Exception} Throws an exception with some description text if anything goes wrong
 */
public function deleteCategory($id) {
    static $catCnt = 0;

    Helper::log("deleteCategory: id = $id");

    try {
        // Open database-connection
        $this->openDatabase();

        // Remove all subcategories recursively
        $stmtSubs = $this->_db->prepare("SELECT Id FROM categories WHERE ParentId = :id");
        $stmtSubs->bindParam(":id", $id, PDO::PARAM_INT);
        $stmtSubs->execute();
        while ($row = $stmtSubs->fetch(PDO::FETCH_ASSOC)) {
            Helper::log("deleteCategory: call recursively to delete subcategory with id = " . $row["Id"]);
            $this->deleteCategory($row["Id"]);
        }

        // All subcategories have been removed -> Now it's time to remove the category itself
        $stmt = $this->_db->prepare("DELETE FROM Categories WHERE Id = :id");
        $stmt->bindParam(":id", $id, PDO::PARAM_INT);

        Helper::log("deleteCategory: before execution, id = $id");
        $stmt->execute();

        // The code from here on never gets executed...
        Helper::log("deleteCategory: after execution, id = $id");

        $catCnt += $stmt->rowCount();

        return $catCnt;
    } catch (Exception $ex) {
        throw new Exception("Deletion of category failed:<br>" . $ex->getMessage());
    }
}

如果我用参数0调用这个函数，我得到这个输出：

31.08.2012 09:39:58: deleteCategory: id = 0
31.08.2012 09:39:58: deleteCategory: call recursively to delete subcategory with id = 1
31.08.2012 09:39:58: deleteCategory: id = 1
31.08.2012 09:39:58: deleteCategory: before execution, id = 1
// Here should be the "after execution"-entry, but instead it "waits" half a minute and starts the whole execution from the beginning...
31.08.2012 09:40:28: deleteCategory: id = 0
31.08.2012 09:40:44: deleteCategory: call recursively to delete subcategory with id = 1
31.08.2012 09:40:44: deleteCategory: id = 1
31.08.2012 09:40:44: deleteCategory: before execution, id = 1

正如你所看到它执行得很好，直到它实际上应该删除id为1的子类别.cute-command永远不会完成，相反它似乎没有做任何事情半分钟，然后它开始整个从id开始的递归。

在第二次“尝试”之后，它只返回内部服务器错误（“服务器遇到内部错误或配置错误，无法完成您的请求......”）

如果我用参数1调用此函数，一切正常，因为永远不会调用递归。

这里发生了什么？

谢谢，

Mik的

Answer 1

挣扎了半天，决定将它贴在这里，贴在这里，发布后再看一遍，看到了问题：

“$ this-＆gt; openDatabase（）;”的递归调用是所有邪恶的根源......

谢谢;）

递归删除树形结构数据

1 个答案: