Thanks, I tried that as well but same issue. QGIS uses SQL Lite.

thanks but where is this placed in the code? Currently, it updates the input dataset in place, I want to be able to have the choice of either updating the input data or updating a copy of it in memory and then saving that data output.

thanks - and how would I set this as an output if I don't want it to alter the input table?

Maybe this should be a new question but the code to run when OK is pressed is in the py file that's created by the plugin (not the xxx_dialog.py but xxx.py). But in that in the def run(self): doesn't recognise the values from the xxx_dialog.py file. So I get errors like field_name = self.mMapLayerCB.currentField() AttributeError: 'Search_Update' object has no attribute 'mMapLayerCB'

Thanks, once we get this how do we use these values when Ok is pressed?