What columns are needed to list the database, schema and table a record comes from?

I am writing queries which read identical tables across databases and schemas and I need the columns to include which schema and table a row comes from. While searching during the creation of this post I came across [this answer](https://stackoverflow.com/a/20576324) SELECT u.*, n.nspname as schema, u.tableoid::regclass::text as table_or_view FROM uses u JOIN pg_class c ON c.oid = u.tableoid JOIN pg_namespace n ON c.relnamespace = n.oid This now includes the schema and the table or view. What joins do I need now to add the database as well?