Failing to connect to mysql

As an aside I think use of the Query Database Smart Service is discouraged as it will appear in the Healthcheck Reports as 

The Query Database node is used X times in all process models. Query rules and CDT-based data store updates are the preferred method of database interaction.

So it might be better to use query entity instead. 

Sorry for the missunderstanding, what I mean is that you should create a new object type "Data Store", then what you usually do to query the DB is you have a Expression rule that uses a!queryEntity

You have some examples here: https://docs.appian.com/suite/help/20.1/Query_Recipes.html

Anyways, I would encourage you to do the appian academy training or read the documentation regarding how to read or write data in teh data store entities and then use those nodes

Sorry for the missunderstanding, what I mean is that you should create a new object type "Data Store", then what you usually do to query the DB is you have a Expression rule that uses a!queryEntity

You have some examples here: https://docs.appian.com/suite/help/20.1/Query_Recipes.html

Anyways, I would encourage you to do the appian academy training or read the documentation regarding how to read or write data in teh data store entities and then use those nodes