DB Global waits

Create Or Replace Force View Sys.Av_db_global_waits (Wait_class,
                                                     Total_waits,
                                                     Pct_waits,
                                                     Time_waited_secs,
                                                     Pct_time
                                                    )

As
   Select   Wait_class, Total_waits,
            Round (100 * (Total_waits / Sum_waits), 2) Pct_waits,
            Round ((Time_waited / 100), 2) Time_waited_secs,
            Round (100 * (Time_waited / Sum_time), 2) Pct_time
       From (Select Wait_class, Total_waits, Time_waited
               From V$system_wait_class
              Where Wait_class != 'Idle'),
            (Select Sum (Total_waits) Sum_waits, Sum (Time_waited) Sum_time
               From V$system_wait_class
              Where Wait_class != 'Idle')
   Order By 5 Desc;