It should be a possibility to delete existing layers that were created before dropping a the 3dcitydb schema. If the user decided to not drop the existing layers before cleaning the schema it work be allowed to do so. For example:
User imports the data to an specific schema inside the DB
User creates and refreshes the layers of the corresponding schema
User clean the schema, like using the cleanup_schema() function
when trying to connect from the plug-in to the schema it won't work since it is empty but the mat views are still created and populated.
It should be a possibility to delete existing layers that were created before dropping a the 3dcitydb schema. If the user decided to not drop the existing layers before cleaning the schema it work be allowed to do so. For example: