Function to check whether the user is at the top level of the network?

if(is_super_admin() && is_network_admin()){
    // do network admin only code
}

http://codex.wordpress.org/Function_Reference/is_super_admin

http://hitchhackerguide.com/2011/02/24/is_network_admin/

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)