अपरिभाषित विधि को कॉल करें क्लोजर ::क्वेरी ()

public function __construct($provider) {
    // invoke the closure/provider/factory
    // so that it returns the mysqli instance
    // which then gets assigned to $this->connection
    $this->connection = $provider();
    $sql = 'SELECT * FROM USERS WHERE ID=' ....
}