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无限分类实现 php

2026-04-02 21:44:31PHP

无限分类的实现方法

无限分类是一种常见的树形结构数据存储方式，适用于商品分类、部门架构等场景。以下是几种常见的实现方式：

邻接表模型（Adjacency List）

邻接表是最简单的实现方式，通过在表中添加一个parent_id字段来建立层级关系。

CREATE TABLE categories (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    parent_id INT DEFAULT NULL,
    FOREIGN KEY (parent_id) REFERENCES categories(id) ON DELETE CASCADE
);

查询某个分类的子分类：

function getChildren($parentId = 0) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
    $stmt = $db->prepare("SELECT * FROM categories WHERE parent_id = ?");
    $stmt->execute([$parentId]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

路径枚举法（Path Enumeration）

在表中添加一个path字段，存储从根节点到当前节点的路径。

CREATE TABLE categories (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    path VARCHAR(255) NOT NULL
);

查询某个节点的所有子节点：

function getChildren($nodeId) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
    $stmt = $db->prepare("SELECT * FROM categories WHERE path LIKE ?");
    $stmt->execute(["%/$nodeId/%"]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

嵌套集模型（Nested Set）

使用left和right值来表示节点在树中的位置。

CREATE TABLE categories (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    lft INT NOT NULL,
    rgt INT NOT NULL
);

查询某个节点的所有子节点：

function getChildren($nodeId) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
    $stmt = $db->prepare("SELECT node.* FROM categories AS node, categories AS parent WHERE node.lft BETWEEN parent.lft AND parent.rgt AND parent.id = ? ORDER BY node.lft");
    $stmt->execute([$nodeId]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

闭包表（Closure Table）

使用单独的表存储节点之间的关系。

CREATE TABLE categories (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL
);

CREATE TABLE category_relations (
    ancestor INT NOT NULL,
    descendant INT NOT NULL,
    depth INT NOT NULL,
    PRIMARY KEY (ancestor, descendant),
    FOREIGN KEY (ancestor) REFERENCES categories(id),
    FOREIGN KEY (descendant) REFERENCES categories(id)
);

查询某个节点的所有子节点：

function getChildren($nodeId) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
    $stmt = $db->prepare("SELECT c.* FROM categories c JOIN category_relations cr ON c.id = cr.descendant WHERE cr.ancestor = ? AND cr.depth > 0");
    $stmt->execute([$nodeId]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

递归实现无限分类

使用递归函数获取所有子分类：

function getAllCategories($parentId = 0, $level = 0) {
    $db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');
    $stmt = $db->prepare("SELECT * FROM categories WHERE parent_id = ?");
    $stmt->execute([$parentId]);
    $categories = $stmt->fetchAll(PDO::FETCH_ASSOC);

    $result = [];
    foreach ($categories as $category) {
        $category['level'] = $level;
        $result[] = $category;
        $result = array_merge($result, getAllCategories($category['id'], $level + 1));
    }
    return $result;
}

无限分类的前端展示

在HTML中展示无限分类：

function displayCategories($categories, $parentId = 0, $level = 0) {
    echo '<ul>';
    foreach ($categories as $category) {
        if ($category['parent_id'] == $parentId) {
            echo '<li>' . $category['name'];
            displayCategories($categories, $category['id'], $level + 1);
            echo '</li>';
        }
    }
    echo '</ul>';
}