Shared/Global Session variable

Is it possible to have a session variable that is shared between different users sessions?

As an example, is it possible to declare something like this:

$todays_color='red';

User 1 Session
echo $_SHARED_SESSION['todays_color']; //outputs: red

User 2 Session
echo $_SHARED_SESSION['todays_color']; //outputs: red

I think you're overcomplicating it. Effectively the same thing can be achieved by saving data in a database or file, but use a function to read and set the value so your code doesn't bloat too much. You can link the sessions to the database entry or file by setting a session variable for each relevant user.

Thanks, I was trying to avoid that using a mysql query for that. I may use an include.

Any advice about whether using includes vs mysql queries is less taxing on server resources?

Actually, includes should be substantially faster and less server intensive overall... It's just a ***** to manage properly. Databases, for all their overhead, are gold for management.