SQL>
SQL> select owner,
2 tablespace_name,
3 sum(bytes)/(1024*1024) total_meg
4 from dba_extents
5 where rownum < 50
6 group by cube (owner,tablespace_name)
7 /
OWNER TABLESPACE_NAME TOTAL_MEG
------------------------------ ------------------------------ ----------
4
SYSTEM 4
SYS 4
SYS SYSTEM 4