Persistence in an external database of mysql using Mosquitto

[WarDoGG]

When I confige the mosquitto.conf file I can implement the persistence with the default mosquitto.db ,but it can't satisfy our need,so I would like to implement the persistence in the external database of mysql ,although I add the code in the mosquitto.conf as follows:\[code\]db_host 127.0.0.1db_name testdb_username rootdb_password 123456\[/code\]I can not still succeed, I don't know whether I config the error.