Select whichever is your actual Moodle db - I'm guessing that's moodledb. Then use the Dump command to dump (export) it out to a file for safekeeping.
However, doing this does not guarantee a clean database: if users are using it there may very well be transactions going on that will be out of sync (especially interactive things like quizzes, forums, grades, etc.) as the dump takes place.
That's one reason why it is better to schedule database dumps for off hours in the middle of the night instead of doing them interactively with a tool like Adminer.
For a complete backup you will also need to backup your /moodledata folder structure too.
Also, you say Moodle backups don't work for you. If you mean the Automated backups, then it's important to know they do not backup the Moodle database. They automate backing up of -courses- using the standard Moodle course backup process so they can be easily restored. They don't and aren't designed to back up the whole Moodle system.