Check total Size for Ram/memory For Oracle

Check total size of Ram/Memory For Each Database :

select decode( grouping(nm), 1, ‘total’, nm ) nm, round(sum(val/1024/1024)) mb
  select ‘sga’ nm, sum(value) val
     from v$sga
   union all
   select ‘pga’, sum(value)
    from v$sysstat
   where name = ‘session pga memory’
   group by rollup(nm)

The Orginial Post from Tom Kyte.

Thank you
Osama Mustafa