Thanks for the confirmation. Indeed, I know (better, I suspected, and was almost 100% sure) that in my case Skipper would be another ERD tool. One clarification: I didn't used MySQL Workbench at all, I used Skipper directly to create the ER model. I didn't used MySQL Workbench in the first place because, as far as I know, it doesn't support inheritance, something that Skipper does. Since my ER model has inheritance, I'll have to find out a way of implement it in MySQL Workbench (or, at least, directly in MySQL).