how to prevent duplicate data added to the user table , I have tried unique indexing ,the user table is not allowing to modify the data .
Check this, it can be for a username or any other attribute, your choice.
https://www.outsystems.com/forums/discussion/77562/how-to-prevent-duplicate-username-or-userno-when-people-in-signup-page/
Kind Regards,
Márcio