Will a plugin able to know is_user_logged_in?

The $current_user global isn’t setup until right before the 'init' action is called. So any code using it shouldn’t be fired until that action or later.

I would also suggest using the get_current_user_id() method instead of getting the global directly.

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