如何启动单个PHP会话？

I'm looking for a way to start a single PHP session, but nothing seems to work.

I've tried doing like this:

session_start($_SESSION['check_rank']);

But it didn't work.. I got the following error:

PHP Notice:  Undefined variable: _SESSION in /Applications/MAMP/MyProjects/teste/teste.php on line 4
PHP Warning:  session_start() expects parameter 1 to be array, null given in /Applications/MAMP/MyProjects/teste/teste.php on line 4

Is there a way to start only a single section?

What is a "single" PHP session? Never heard of it.

session_start() takesno parameter, it just starts the session. If you want to call/start a named session, you have to use session_name().

e.g.

<?php
session_name("my-session");
session_start();

$_SESSION is to store session variables,

e.g.

<?php
session_name("my-session");
session_start();

$_SESSION["foo"] = "bar";