I spent ages combing the web for a decent ERD tool for the Mac, and for some time resigned to using dbwrench, a java binary the provides decent but limited functionality and is free of charge.
The choice of tools for ERD work is much narrower than what’s available on Linux or the PC, where something like DBDesigner 4 is fantastic and can handle pretty much any job you throw at it.
Then finally I stumbled across SQLEditor and I have to say it’s excellent. It has a sharp and clean GUI with the attention to detail you’d expect from a first rate Mac app. However there is a price tag, $79, and after years of being able to depend on high quality apps that are available for free, I have to say paying such a price takes some getting used to. In this case I think it’s totally worth it and would recommend this tool for any Mac-based software developer.
NB: As phpMyAdmin has collapsed in recent versions, you might also be looking for a decent MySQL client, Sequel Pro is the clear leader.