Map Nginx Query String

I have a webapp e.g example.com is mapped with some embedded url in
nginx.

server {

location / {

set $args id=201;

try_files $uri $uri/ $uri/index.php /index.php;

}

}

When I visit my site example.com and example.com/id=201 it renders
same
page.

but when i visit example.com/index.php it renders different page.

Is there any way to map example.com/index.php on the same page in
which
example.com is mapped? ( here example.com/id=201)

Posted at Nginx Forum:
http://forum.nginx.org/read.php?2,252730,252730#msg-252730