Действительно ли возможно создать самоподписанный промежуточный CA для ssl?
Выполните запрос в mysql непосредственно. Первый доступ mysql из командной строки:
sudo mysql -p
Затем выберите базу данных, которую Вы хотите использовать
show databases;
use databaseiwant;
Теперь выполните запрос на таблице, в которой необходимо найти дубликаты
show tables;
SELECT fieldtocheckduplicates, COUNT(fieldtocheckduplicates) AS NumOccurrences FROM tabletocheck GROUP BY fieldtocheckduplicates HAVING ( COUNT(fieldtocheckduplicates) > 1 );
Regularly an intermediate CA needs a valid signature (also not expired) from a trusted CA and also the usage restriction tag CA:true. Normally intermediate CAs are not directly listed in the trust database by verifying clients. Therefore, when a service sends its own certificate which is signed by an intermediate CA (for example when establishing a TLS session) it should also send all the intermediate CA certificates between itself and the root CA, so the verifying client can actually build a trust chain between the two ends of the chain.
A self-signature, as you are talking about in the title of your question, would make this either a stand-alone certificate or if it has the CA:true flag it would make the certificate a root CA itself.