Cache

I used fastcgi_cache. It works so great

But I have a website that let someone to login with their own username.
Sometimes it’s giving me onother username.

Is there any ways if using fastcgi_cache, but exclude a text that’s
grabbed
from database? Or somethink that I can prevent that problem?

You could modify your script to put the username (or other uniquely
identifying code) in the url somewhere, so that it would split the
cache based on this information.