php mysql单例模式

<?php
class Database {
    private static $instance;
    private $connection;

    private function __construct() {
        $this->connection = new mysqli('localhost', 'username', 'password', 'database');
        if ($this->connection->connect_error) {
            die("Connection failed: " . $this->connection->connect_error);
        }
    }

    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new Database();
        }
        return self::$instance;
    }

    public function getConnection() {
        return $this->connection;
    }

    private function __clone() {}
    private function __wakeup() {}
}

// 使用示例
$db = Database::getInstance();
$conn = $db->getConnection();
$result = $conn->query("SELECT * FROM table_name");
while ($row = $result->fetch_assoc()) {
    // 处理数据
}
?>