Thanks

Otherwise, I found in the browser the following address filled in the address bar :

http:// localhost:1158/em/console/database/instance/sitemap?event=doLoad&target=base1&type=oracle_database

So I have created a copy of the link for OEM, put this url in the "URL" field on the link, changed "base1" to "base2", and I get a correct link to open OEM for "base2".

Starting and shutdowning the correct database (or both) may be done with SQL*Plus, connect sys/psw@base1 (or 2) as sysdba, then startup or shutdown.

Thanks again and good evening.