Yes, there was a "Using Moodle databases" forum. See:
https://docs.moodle.org/19/en/MySQL#See_also
https://docs.moodle.org/20/en/MySQL#See_also
https://docs.moodle.org/21/en/MySQL#See_also
https://docs.moodle.org/22/en/MySQL#See_also
https://docs.moodle.org/23/en/MySQL#See_also
https://docs.moodle.org/24/en/MySQL#See_also
https://docs.moodle.org/25/en/MySQL#See_also
There used to be a separate forum for this, but as part of the great forum re-organisation, it was merged into some others, mainly the general developer forum (the old forum was very low traffic).
Note that there is always confusion between Moodle's database activity, and the database that Moodle uses to store all the application data. I guess that is inevitable and unsolvable. But, anyway, not having two forums with 'Database' in the name probably helps.
I think most of the confusion between these two (and a few other forums) is that most people scan not read. When they look for "database" and see "database" as the first word, they may not even look at the 2nd word. I think there was a suggestion to name the forums with category keyword first, like "Activity: Database" and "Moodle core: Database" which would have reduced the confusion but that suggestion was not followed.