There must be another way of doing this...I need some pages to be members only and some open to the public. Anytime I have the sql call in the beginning, I get "page not found"

If I have this, then the page is viewable by everyone. Another problem is that my php code on those special pages require information from the database and that information is not displaying.

Code:
require './include/config.php';

if ($page_info['page_members_only'] == 1)
{
    User::is_logged_in();
}

function show_page_not_found()
{
    header("HTTP/1.0 404 Not Found");
    echo "<html><head><title>Page Not Found</title></head><body>Page Not Found</body></html>";
    exit(0);
}