关于031的一道题

admwby1hy

You need to determine the amount of space currently used in each
tablespace.You can retrieve this information in a single SQLstatement using only one DBA view in the FROM clause providing you use either the  ? or ? DBA view
a. dba_extents
b. dba_segments
c. dba_data_files
d.dba_tablespace
我觉的应该选a b
怎么答案是 a c
请高手评判

sshd

i think it's ab

# available space
select TABLESPACE_NAME, sum(BYTES)
from dba_data_files group by TABLESPACE_NAME;

# allocated space
select TABLESPACE_NAME, sum(BYTES) from dba_segments
group by TABLESPACE_NAME;

# allocated space
select TABLESPACE_NAME, sum(BYTES)
from dba_extents
group by TABLESPACE_NAME;