user_list_cells Real name sometimes shows empty

Yes the real name is sometimes empty, users may skip to input real name, because its not mandatory,  Incase if they didnt input, the user_list_cells function will be showing an empty list. so lets change the query to be like this.

 $sql = " SELECT user_id, IF(real_name = ' ', user_id, real_name) FROM ".TB_PREF."users";

suppose if the real name empty, it will show the user_id in it. which will avoid confusions