php查询子节点数据库

<?php
$host = 'localhost';
$dbname = 'testdb';
$user = 'username';
$pass = 'password';

try {
    $pdo = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $user, $password);

    function getChildren($pdo, $parentId) {
        $stmt = $pdo->prepare("SELECT id, name FROM categories WHERE parent_id = :parentId");
        $stmt->execute(['parentId' => $parentId]);
        $children = $stmt->fetchAll(PDO::FETCH_ASSOC);

        foreach ($children as &$child) {
            $child['children'] = getChildren($pdo, $child['id']);
        }

        return $children;
    }

    $rootCategoryId = 1; // 假设我们要查询ID为1的类别的所有子类别
    $children = getChildren($pdo, $rootCategoryId);

    print_r($children);
} catch (PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}
?>