Question

I have a query which runs fine if I manually declare $add to be a value (30 for example) by when I try to set it to the user_id session the query fails.

// $add = 30;
// The line above works
$add = mysql_real_escape_string($_SESSION['user_id']);
$query = "UPDATE mytable SET act=0, add=$add WHERE id=$selected_user";

Any ideas where I’m going wrong.

Answer 1

When using sessions you always need to specify this before any $_SESSION usage like this:

session_start();
//now you are able to use this
$_SESSION['user_id'] = 30;

By the other hand, I got the same problem as you before and what you need to do is to
put the $_SESSION['user_id'] in a variable, then you will be able to pass it to the mysql_real_escape_string without problems.

$id = $_SESSION['user_id'];
//now use this:
$add = mysql_real_escape_string($id);

Hope this helps.