protected function _buildSetPart($parts, $query, $generator)
    {
        $set = [];
        foreach ($parts as $part) {
            if ($part instanceof ExpressionInterface) {
                $part = $part->sql($generator);
            }
            if ($part[0] === '(') {
                $part = substr($part, 1, -1);
            }
            $set[] = $part;
        }

        return ' SET ' . implode('', $set);
    }