Provide the ability to mimic a user:

In the Oracle World this requires a grant command and a special kind of connect command - the username would be a combination of my username and the username I would like to login using my credentials.
for example:
CREATE USER proxybenutzer IDENTIFIED BY proxypasswort;
(or use an existing database user)
Grant privilege:
ALTER USER scott GRANT CONNECT THROUGH proxybenutzer;
scott is the user account in which I would like to login
The connect- Statement changes for the proxy-user:
connect proxybenutzer[scott]/proxypasswort
Then I can connect as user "proxybenutzer" to the account "scott".