How to set environment variables on a session level

Databases
1

It seems that below code sets the environment value on a system level.
Is there any way to set it with a session level? I mean I need to set the value when I connect to local PostgreSQL database and I don’t want other session to find the value.

System.EnvironmentVariable("USERNAME")
2

there is only one environment variable list per process.
But you can of course change it after connecting or better pass username via connection string.

3

Does it mean that other processes are not affected with the environment variable My application sets?

4

yes, you only change them for your app.

For all apps, you need to change Windows registry on Windows or .profile file on Linux or some other file on Mac.

5

Clear. Thanks a lot!