Integrity across multiple database types

Since most use SQL server, I thought I would post the question here.
Is it possible, or is there a product or DBMS that enforces referential integrity across multiple databases and database types? Such as SQL Server, Oracle, etc...
Thanks,
ZathDRI(declarative referential integrity) is Peter Chen ERD 1976 enable data delete and update in multiple tables at the same time but you cannot set it up across two databases but if you plan very well you can use linked server to access separate DRI(declarative referential integrity) rules setup in two databases. CASCADE ON DELETE, CASCADE ON UPDATE, ON DELETE NO ACTION and ON UPDATE NO ACTION the later will not allow delete or update. Run a search for all in the BOL(books online). Hope this helps.|||Thanks, just the start I needed.
Zath