Would it work to simply disable the "not empty" validation in FileMaker?
Nope! and that's another irritating bug/feature. The field definition is pretty much useless with mySQL DBs. If you modify the validation in the fields definition, not only won't it update the online DB, but also if you leave and come back to the field definitions window, you will see that FM will sneak behind your back, and reset the field validation, so it matches the online version, and that, without even a small warning.
In fact, in V9, I even found that FM sometimes kept its validation, contrary to the online version. If often happened if the definition window was still open, while at the same time, going online to change the mySQL validation directly, even when synching the fields! I think that v.11 no longer has that problem though.
To be honest, at this point, I hope that it's just me not figuring out how to do a few things, but otherwise, I think that FM's CLAIM OF SUPPORTING MYSQL DBS JUST AS IF THEY WERE FM DBS TO BE VASTLY OVERSTATED... (sorry for me shouting, but I very much hope someone at FM will wake up and get the message).
I understand that there are differences in between FM and mySQL DBs that must be hard to fill. But nothing that a few experienced programmers can't fix over a few years period.
It's sad, because mySQL dbs are ubiquitous these days. And I love using FM in general.
It would be so great to be able to work with mySQL Dbs, just as if they were FM DBs (as the ads claimed), out of the box, without the need to pay for an extra Actual Technologies plugin !
Since this was rather new when v.9 came out, maybe it was ok, but not at v.11!