Using the Edit Databases facility:
When trying to edit a table field length I always get this error:
Failed to save field : SQL alter table adverts modify caption varchar(200) not null default none failed : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘none’ at line 1
Yeah, you shouldn’t get SQL errors when using Virtualmin 
I’d go ahead and file a bug report regarding that.
Thanks!
-Eric
It’s possible to do things in the fields that could trigger SQL errors (Webmin doesn’t do SQL syntax or type checking, and leaves it up to the database to do so)…so it’s not impossible to get SQL errors when using the module (and it wouldn’t indicate a bug in many cases). But, in this case, it does sound like a bug worth filing.
Note also that if you have the Perl MySQL module installed, the robustness and performance of Webmin’s MySQL module is usually better (though it also occasionally has had its own bugs).
I have decided not to use it.
I will just write little php scripts to modify my database if I need to.