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php 实现无限分类

2026-01-14 13:29:07PHP

无限分类的实现方法

无限分类通常用于构建多层级结构的数据，如商品分类、菜单管理等。以下是几种常见的实现方式：

邻接列表模型（Adjacency List）

这是最简单的实现方式，每个分类记录存储其父分类的ID。

// 数据库表结构示例
CREATE TABLE categories (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(255) NOT NULL,
    parent_id INT DEFAULT NULL,
    FOREIGN KEY (parent_id) REFERENCES categories(id)
);

// 获取所有分类
function getCategories($parentId = null) {
    $categories = [];
    $query = "SELECT * FROM categories WHERE parent_id " . ($parentId === null ? "IS NULL" : "= " . (int)$parentId);
    $result = mysqli_query($connection, $query);

    while ($row = mysqli_fetch_assoc($result)) {
        $row['children'] = getCategories($row['id']);
        $categories[] = $row;
    }

    return $categories;
}

嵌套集模型（Nested Set）

这种模型通过left和right值来表示层级关系，查询效率高但维护复杂。

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

// 获取整个树
function getFullTree() {
    $query = "SELECT * FROM categories ORDER BY lft";
    $result = mysqli_query($connection, $query);

    $tree = [];
    $stack = [];

    while ($row = mysqli_fetch_assoc($result)) {
        $node = $row;
        $node['children'] = [];

        while (!empty($stack) && $stack[count($stack)-1]['rgt'] < $node['rgt']) {
            array_pop($stack);
        }

        if (!empty($stack)) {
            $stack[count($stack)-1]['children'][] = &$node;
        } else {
            $tree[] = &$node;
        }

        $stack[] = &$node;
    }

    return $tree;
}

路径枚举（Path Enumeration）

存储从根到当前节点的完整路径。

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

// 获取子分类
function getChildren($path) {
    $query = "SELECT * FROM categories WHERE path LIKE '" . mysqli_real_escape_string($connection, $path) . "%'";
    $result = mysqli_query($connection, $query);

    $categories = [];
    while ($row = mysqli_fetch_assoc($result)) {
        $categories[] = $row;
    }

    return $categories;
}

闭包表（Closure Table）

使用单独的表存储节点之间的关系。

php 实现无限分类

CREATE TABLE categories (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(255) 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)
);

// 获取子树
function getSubtree($categoryId) {
    $query = "SELECT c.* FROM categories c
              JOIN category_relations cr ON c.id = cr.descendant
              WHERE cr.ancestor = " . (int)$categoryId . "
              ORDER BY cr.depth";

    $result = mysqli_query($connection, $query);

    $tree = [];
    while ($row = mysqli_fetch_assoc($result)) {
        $tree[] = $row;
    }

    return $tree;
}