upsert.md

    public function qwerty(DatabaseAdapter $adapter): \Generator
    {
        /** @var array|null $customerInfo */
        $customerInfo = yield fetchOne(
            yield $adapter->execute('SELECT * FROM customers WHERE id = ?', [10])
        );

        if(null === $customerInfo)
        {
            $sequence = yield fetchOne(
                yield $adapter->execute('SELECT nextval(\'serial\')')
            );

            print_r($sequence['nextval']);
        }

        print_r($customerInfo);
    }
    ```