I got the attached error message when trying to create a relationship between 2 tables, and don't know what it means (have not seen it before). The funny thing is that I have a working Derby database with the same layout and relationship. I exported all the data, imported into a mySQL version, and then when trying to recreate the relationship, it gives me the error. This is in 14.12.15.
just a quick idea. Could you please try to create the relationship vice versa? I do not mean changing the direction of the relationship, but just the order of actions in IJC:
If you created the relationship between A and B, by r-clicking entity A and creating the relationship to B, could you try to create the relationship by r-clicking entity B instead and creating the relationship to A?
MySQL is slightly more picky than Derby and for example if you create Many-to-one relationship, it is better to create the relationship from the "many" side of it. If you try to create it from the "one" side of the relationship, this error can appear
I hope this helps