If you have made changes to your underlying schema by adding new fields, you can click on the **‘Source refresh’** button to bring in the new columns to your base view. In general, Source refresh will sync the base view with the data source. As of now, this is the only way to perform the actual source refresh.
Besides,we have a [REFRESH statement](https://community.denodo.com/docs/html/browse/latest/vdp/vql/refresh_views/refresh_views#refresh-statement) to refresh the data of a view. This command updates the data of the underlying data source. But it is supported only by the base views created using the [CREATE_REMOTE_TABLE](https://community.denodo.com/docs/html/browse/latest/vdp/vql/stored_procedures/predefined_stored_procedures/create_remote_table#create-remote-table) stored procedure.
In order to add new columns, I would use the Create or Replace table statement. For instance, if I have three fields and want to add a fourth field, then I will include the additional column in the Create Or Replace statement. You can have a look at the section [Creating a Base View](https://community.denodo.com/docs/html/browse/latest/vdp/vql/creating_a_base_view/creating_a_base_view#creating-a-base-view) of the Virtual DataPort VQL Guide for more information.
And also, I would like to add that deleting a base view that has dependent views, deletes the dependent views automatically. However, if you delete a base view that is used in an interface view, that interface is not deleted automatically because only the implementation has been removed.
Hope this helps!