private function getNextOperator(string $column): ?string
    {
        reset($this->fragments['where']);

        while (key($this->fragments['where']) !== $column) {
            next($this->fragments['where']);
        }
        
        next($this->fragments['where']);

        $key = key($this->fragments['where']);

        return $this->fragments['where'][$key]['operator'];
    }