Postgres allows:
UPDATE dummy
SET customer=subquery.customer,
address=subquery.address,
partn=subquery.partn
FROM (SELECT address_id, customer, address, partn
FROM /* big hairy SQL */ ...) AS subquery
WHERE dummy.address_id=subquery.address_id;
This syntax is not standard SQL
P. Eisentraut. Mitp-Verlag, Bonn, (2003)das Insider-Wissen der PostgreSQL-Entwickler, mit ausführlicher SQL-Beschreibung, den PostgreSQL-Server sicher beherrschen; übers. von Peter Eisentraut.