protected function quoteNameWithSeparator(string $spec, string $sep, int $pos): string
    {
        $len = strlen($sep);
        $part1 = $this->quoteName(substr($spec, 0, $pos));
        $part2 = $this->quoteIdentifier(substr($spec, $pos + $len));

        return "{$part1}{$sep}{$part2}";
    }