$q = "UPDATE users SET sessionid=".session_id()." WHERE userid=".$_POST['username'];

[reecieboy]

Whats wrong with the above?

Problem with query: UPDATE users SET sessionid=27768e4a7b8a093671bf7c4f1e883ed9 WHERE userid=user
You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'a7b8a093671bf7c4f1e883ed9 WHERE userid=user' at line 1

[kenrbnsn]

You need to surround any text with single quotes:
[code]<?php
$q = "UPDATE users SET sessionid='".session_id()."' WHERE userid='".$_POST['username'] . "'";
?>[/code]

Ken