Relation from database to filename of e.g. table - Mailing list pgsql-admin

Hello Admins

Can someone please tell me, which relation gives me the link between a
database and a table?

I want to find out, which table belongs to which database in a cluster.

Something like

SELECT d.datname, c.relname
FROM pg_database d, pg_class c, pg_xxx x
WHERE d.oid = x.oid
   AND x.oid = c.relfilenode

But I did not find the pg_xxx.

Thanks
Oli