Question

我正在尝试使用PHP和MySQL创建嵌套的无序列表（通过CodeIgniter，虽然我不认为这是相关的）。

我见过很多解决方案似乎适用于具有两级嵌套的列表，但我需要的解决方案必须有三个级别。这是我需要的东西：

<ul>
    <li>Top Level, Item 1
        <ul>
            <li>Second Level, Item 1
                <ul>
                    <li>Third Level, Item 1</li>
                    <li>Third Level, Item 2</li>
                    <li>Third Level, Item 3</li>
                </ul>
            <li>Second Level, Item 2
                <ul>
                    <li>Third Level, Item 4</li>
                    <li>Third Level, Item 5</li>
                    <li>Third Level, Item 6</li>
                </ul>
            </li>
        </ul>
    </li>
</ul>

我的数据库的输出基本上是：

TOP LEVEL | SECOND LEVEL | THIRD LEVEL
Item 1 | Item 1 | Item 1
Item 1 | Item 1 | Item 2
Item 1 | Item 1 | Item 3
Item 1 | Item 2 | Item 4
Item 1 | Item 2 | Item 5
Item 1 | Item 2 | Item 6

我已经尝试了从数据库输出，使用变量来注册我在哪个级别等等但是我在关闭每个列表时陷入了可怕的混乱。

有人可以建议这样做吗？

Answer 1

<强>查询

SELECT a.item, b.item, c.item FROM TOP_LEVEL a JOIN SECOND_LEVEL b ON b.level = a.level JOIN THIRD_LEVEL c ON c.level = b.level ORDER BY a.item, b.item, c.item

<强>码

<?php
$q = "SELECT a.item, b.item, c.item FROM TOP_LEVEL a JOIN SECOND_LEVEL b ON b.level = a.level JOIN THIRD_LEVEL c ON c.level = b.level ORDER BY a.item, b.item, c.item ";
...... your database stuff......
...... resulting array should be two-dimensional `$items` ......
$c = 0;
echo "<ul>\n";
while ($c < count($items)) {
    for ($j = 0; $j < count($items[$c][0]); $j++) {
        echo "<li>$items[$c][0]\n";
        echo "<ul>\n";
        for ($k = 0; $k < count($items[$c][1]); $k++) {
            echo "<li>$items[$c][1]\n";
            echo "<ul>\n";
            for ($i = 0; $i < count($items[$c][2]); $i++) {
                echo "<li>$items[$c][2]<\li>\n";
                $c++;
            }
            echo "</ul>\n";
            echo "</li>\n";
                    $c++;
        }
        echo "</ul>\n";
        echo "</li>\n";
            $c++;
    }
    echo "</ul>\n";
}
?>

Answer 2

感谢所有的帮助，但我想我已经以完全不同的方式解决了这个问题！

@DevishOne提供的解决方案让我思考，并且使用它作为一个模板，我添加了变量来识别是应该打开还是关闭新的子列表或子子列表。

我并不是说这是万无一失的，我也没有声称它特别有效，但它确实适合我（到目前为止！）

我的解决方案：

//Placeholder variables
$current_top = '';
$current_second = '';
$current_third = '';

echo '<ul>';
foreach($array as $row) {
    //If it is a new top level item...
    if ($row['top_level'] != $current_top) {
        //If it isn't the very first top level item...
        if ($current_top != '') {
            //Close off all of the other first, second, and third level branches.
            echo '</ul></li></ul></li>';
        }
        //Echo the top level item, including the start of the sub-list.
        echo '<li>'.$row['top_level'].'<ul>';
        //Set the current top level variable to the current top level item.
        $current_top = $row['top_level'];
        //Set the current second level variable back to null (if it isn't already).
        $current_second = '';
    } 
    //If it is a new second level...
    if ($row['second_level'] != $current_second) {
        //If it isn't the very first second level item...
        if ($current_second != '') {
            //Close off all of the other second and third level branches.
            echo '</ul></li>';
        }
        //Echo the second level item, including the start of the sub-sub-list.
        echo '<li>'.$row['second_level'].'<ul>';
        //Set the current second level variable to the current second level item.
        $current_second = $row['second_level'];
        //Set the current third level variable back to null (if it isn't already).
        $current_third = '';
    } 
    //If it is a new third level...
    if ($row['third_level'] != $current_third) {
        //Echo the third level item, and close it off.
        echo '<li>'.$row['third_level'].'</li>';
        //Set the current third level variable to the current third level item.
        $current_third = $row['third_level'];
    }
}
echo '</ul>';

PHP和MySQL中的嵌套列表

2 个答案: