PHP & MySQL 中的嵌套注释

Question

我搜索了论坛，但没有得到权威的答案。我想以这样的方式实现嵌套的注释结构：

<ul>
    <li>This is the parent first comment!
        <ul>
            <li>This is the reply for the first parent comment!
                <ul>
                    <li>This is a reply for the first reply of the parent comment!</li>
                    <li>This is a third reply for the first parent comment!</li>
                </ul>
            </li>
            <li>This is another reply for first parent comment!</li>
        </ul>
    </li>
    <li>This is gonna be parent second comment!
        <ul>
            <li>This is a reply for the second comment!</li>
        </ul>
    </li>
    <li>This is fourth parent comment!</li>
</ul>

我的表的转储如下：

+----+------------------------------------------------------------+--------+
| id | text                                                       | parent |
+----+------------------------------------------------------------+--------+
|  1 | This is the parent first comment!                          |      0 |
|  2 | This is gonna be parent second comment!                    |      0 |
|  3 | This is the reply for the first parent comment!            |      1 |
|  4 | This is another reply for first parent comment!            |      1 |
|  5 | This is a reply for the first reply of the parent comment! |      3 |
|  6 | This is a reply for the second comment!                    |      2 |
|  7 | This is a third reply for the first parent comment!        |      3 |
|  8 | This is fourth parent comment!                             |      0 |
+----+------------------------------------------------------------+--------+

我知道如何使用 mysql_query() 和 while() 循环。 PHP & MySQL 的初学者。请帮帮我。

Answer 1

有几种不同的方法可以在 MySQL 中存储分层数据。查看 Bill Karwin 的 presentation，它展示了四个选项。

• 邻接列表
• 路径枚举
• 嵌套集
• 闭包表

---

您正在使用邻接列表模型来存储分层数据，但不幸的是，这是您可以选择用于查询子树的最难模型。

您的选择是：

• 更改为其他型号。
• 将查询限制为 n 级深度。
• 使用存储过程递归查询。有关这方面的更多信息，请参阅 Quassnoi 的系列文章 - Hierarchical queries in MySQL。

Answer 2

我为我的博文做了类似的事情。然而，我只是尝试了相同的数据。当您说 nested cmets 时，最好以这种方式使用 nested functions：

function getComments($parent)
{
    # Get the data from SQL.
    # Check if it has nested comments.
    if (hasComments())
        getComments($child); # $child is the ID of the current comment.
}

为了做到这一点，我已将您的数据导入 MySQL 并尝试了以下操作：

<?php
    mysql_connect('localhost', 'root');
    mysql_select_db('nestedcomments');
    function getComments($parent)
    {
        $res = mysql_query("SELECT * FROM `nestcomm` WHERE `parent` = $parent");
        if (mysql_num_rows($res))
        {
            echo "<ul>\n";
            while (($dat = mysql_fetch_array($res)) !== false)
                echo "<li>", $dat["text"], getComments($dat["id"]), "</li>\n";
            echo "</ul>\n";
        }
        else
            echo ($parent === 0) ? 'No Comments!' : "";
    }
    getComments(0);
?>

正如我之前所说，我使用了嵌套函数，并且正如你所问的那样，输出几乎相同（没有大括号）：

<ul>
<li>This is the parent first comment!<ul>
<li>This is the reply for the first parent comment!<ul>
<li>This is a reply for the first reply of the parent comment!</li>
<li>This is a third reply for the first parent comment!</li>
</ul>
</li>
<li>This is another reply for first parent comment!</li>
</ul>
</li>
<li>This is gonna be parent second comment!<ul>
<li>This is a reply for the second comment!</li>
</ul>
</li>
<li>This is fourth parent comment!</li>
</ul>

希望这会有所帮助。