Where Can i connect database in mattermost with linux cento7 OS?

       Hello. I want to connect database(Mysql)  for playing query in mattermost ?

How should I do My PC is linux Cento7 OS and run mattermost with this command
"docker run --name mattermost-preview -d --publish 8065:8065 mattermost/mattermost-preview". Now I use the other PC with Puttery. Please suggest me.