Can it support access to SQL with unity basic ios?
Yes
U3 supports plugins for both, Unity iOS Pro as well as the normal Unity iOS
Great!
But can someone explain this further for me
Native Code Plugins Support
Have a custom native library that you absolutely must use? Use a C, C++, Objective-C or Java plugin to directly call into it. See plugin docs
According to the license comparison, it doesnt allow NC Plugin support. Or has it not been update.
Unity free does not offer native code plugins.
But Unity iOS offers it on both licenses offer it and the comparision table you find on the store page shows the same 
With iOS basic, will it allow me to build the editor as well?
We are trying to build our selves our own in-house kit that will allow making games easier for us. Is this possible with the ios basic?