For some reason, it is necessary to display data from the mysql database in two different tree views.
Example
Tree View 1 (using a list tag):
<li>level1 (Root) <ul> <li>level2</li> <li>level2 <ul> <li>level3</li> <li>level3 <ul> <li>level4</li> <li>level4</li> </ul> </li> </ul> </li> <li>level2 <ul> <li>level3</li> <li>level3 <ul> <li>level4</li> <li>level4</li> </ul> </li> </ul> </li> </ul> </li>
Type of tree 2:
I am currently working on this php script:
<?php $servername = "localhost"; $username = "root"; $password = "psswd_here"; $dbname = "db_here"; $conn = new mysqli($servername, $username, $password, $dbname); if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); } $data = array(); $index = array(); $sql2 = "SELECT * FROM categories ORDER BY name"; $result2 = $conn->query($sql2); if ($result2->num_rows > 0) { while ($row2 = $result2->fetch_assoc()) { $id = $row2["id"]; $parent_id = $row2["parent_id"] === NULL ? "NULL" : $row2["parent_id"]; $data[$id] = $row2; $index[$parent_id][] = $id; } } else { echo "0 results"; } $conn->close(); function display_child_nodes($parent_id, $level) { global $data, $index; $parent_id = $parent_id === NULL ? "NULL" : $parent_id; if (isset($index[$parent_id])) { foreach ($index[$parent_id] as $id) { echo str_repeat("-", $level) . $data[$id]["name"] . "<br>"; display_child_nodes($id, $level + 1); } } } echo '<ul>'; display_child_nodes(NULL, 0); echo '</ul>'; ?>
OUTPUT:
Electronics -Cameras and Photography --Accessories --Camcorders --Digital Cameras -Cell Phones and Accessories --Accessories --Cell Phones --Smartphones -Computers and Tablets --Desktops --Laptops --Netbooks --Tablets ---Android ---iPad -TV and Audio --Home Audio --Speakers and Subwoofers --Televisions ---CRT ---LCD ---LED ---Plasma
Here is the database schema.
-- phpMyAdmin SQL Dump -- version 4.4.12 -- http://www.phpmyadmin.net -- -- Host: 127.0.0.1 -- Generation Time: Oct 21, 2015 at 09:16 AM -- Server version: 5.6.25 -- PHP Version: 5.6.11 SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO"; SET time_zone = "+00:00"; /*!40101 SET @ OLD_CHARACTER_SET_CLIENT=@ @CHARACTER_SET_CLIENT */; /*!40101 SET @ OLD_CHARACTER_SET_RESULTS=@ @CHARACTER_SET_RESULTS */; /*!40101 SET @ OLD_COLLATION_CONNECTION=@ @COLLATION_CONNECTION */; /*!40101 SET NAMES utf8mb4 */; -- -- Database: `binary` -- -- -------------------------------------------------------- -- -- Table structure for table `categories` -- CREATE TABLE IF NOT EXISTS `categories` ( `id` int(10) NOT NULL, `parent_id` int(10) DEFAULT NULL, `name` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL ) ENGINE=InnoDB AUTO_INCREMENT=25 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; -- -- Dumping data for table `categories` -- INSERT INTO `categories` (`id`, `parent_id`, `name`) VALUES (1, NULL, 'Electronics'), (2, 1, 'Cameras and Photography'), (3, 1, 'Computers and Tablets'), (4, 1, 'Cell Phones and Accessories'), (5, 1, 'TV and Audio'), (6, 2, 'Digital Cameras'), (7, 2, 'Camcorders'), (8, 2, 'Accessories'), (9, 3, 'Laptops'), (10, 3, 'Desktops'), (11, 3, 'Netbooks'), (12, 3, 'Tablets'), (13, 4, 'Cell Phones'), (14, 4, 'Smartphones'), (15, 4, 'Accessories'), (16, 5, 'Televisions'), (17, 5, 'Home Audio'), (18, 5, 'Speakers and Subwoofers'), (19, 16, 'CRT'), (20, 16, 'LCD'), (21, 16, 'LED'), (22, 16, 'Plasma'), (23, 12, 'Android'), (24, 12, 'iPad'); -- -- Indexes for dumped tables -- -- -- Indexes for table `categories` -- ALTER TABLE `categories` ADD PRIMARY KEY (`id`); -- -- AUTO_INCREMENT for dumped tables -- -- -- AUTO_INCREMENT for table `categories` -- ALTER TABLE `categories` MODIFY `id` int(10) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=25; /*!40101 SET CHARACTER_SET_CLIENT=@OLD _CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD _CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD _COLLATION_CONNECTION */;