PHP和MySQL中的嵌套列表(Nested Lists in PHP and MySQL)

PHP和MySQL中的嵌套列表(Nested Lists in PHP and MySQL)

我试图使用PHP和MySQL创建一个嵌套的无序列表（通过CodeIgniter，虽然我不认为这是相关的）。

我已经看到了许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

我已经尝试通过数据库的输出，使用变量来注册我在哪个级别等但是我陷入了关闭每个列表的可怕混乱。

有谁能建议这样做的方法？

I am trying to create a nested unordered list using PHP and MySQL (through CodeIgniter, though I don't think that is relevant).

I've seen a number of solutions that appear to work for lists that have two levels of nesting, but the solution I need has to have three levels. This is the sort of thing I need:

<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>

The output from my database is, essentially:

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

I've tried going through the output from the database, using variables to register which level I am on etc. but I get into an awful mess with closing off each list.

Can anyone suggest a way of doing this?

最满意答案

询问

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

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"; } ?>

Thanks for all the assistance, but I think I've cracked it myself, in quite a different way!

The solution provided by @DevishOne got me thinking, and, using that as a bit of a template, I added in variables to identify whether a new sub-list or sub-sub-list should be opened or closed.

I'm not claiming this is foolproof, and neither am I claiming it is particularly efficient, but it does the job for me (so far!)

My solution:

//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>';