I can't find the free ERD tool that I used years ago when I was dabbling in database stuff. It wasn't great but it was enough for my needs. Probably would be too simple for any real use though.

Similarly, ERD tools may have a variety of symbols,, since the data modeling industry has not achieved standardization, and these notations include Crow’s Foot, IDEF1X, Barker, and others. Levels of ...