Setting a database(user) to single user mode?

[Amit Paleja]

Hi

I want to set a particular user (database) to single user mode so that only one user at a time can access it. This is required so as to import data from another user on the same server after which i wish to revert the user to multi user mode.

I tried to achieve this with the following query but in vain:
ALTER SYSTEM ENABLE RESTRICTED SESSION

This sets the entire database server to single user mode and not the user (database) that I want to (the one that am currently connected to).

Is there a way to achieve this?

Amit