Oracle 查询某张表所占空间

select OWNER, t.segment_name, t.segment_type, sum(t.bytes / 1024 / 1024) mmm from dba_segments t where t.owner = '用户名' and t.segment_type='TABLE' and t.segment_name='表名' group by OWNER, t.segment_name, t.segment_type order by mmm desc;