script to find out sga component usage in oracle database?

elect name, round(sum(mb),1) mb, round(sum(inuse),1) inuse
            from (select case when name = 'buffer_cache'
                              then 'db_cache_size'
                           when name = 'log_buffer'
                             then 'log_buffer'
                            else pool
                        end name,
                     bytes/1024/1024 mb,
                        case when name <> 'free memory'
                       then bytes/1024/1024
                      end inuse
                 from v$sgastat
         )group by name;