After creating Materialized Table in Virtual DataPort, I could create derived views over the created Materialized Table based on the requirement.
For example, if I want to add new fields in my output, then I would create a Selection view over the Materialized Table and add the output fields as required. Similarly, I could create different derived views as required.
Generally, it is possible to insert rows into a Materialized Table but it is not possible to delete or update them. Also, Update operations on Materialized Tables is not allowed. In scenarios where I need to update the Materialized Tables, I would either create a new materialized table or if the requirement can be achieved using a derived view, then I would create a derived view over the materialized table.
You could take a look at [Creating Derived Views](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/creating_derived_views/creating_derived_views#creating-derived-views) section under the Virtual DataPort Administration Guide and [Materialized Tables](https://community.denodo.com/docs/html/browse/7.0/vdp/vql/materialized_tables/materialized_tables#materialized-tables) section under the Virtual DataPort VQL Guide.
Hope this helps!