oracle查询表类型和所占空间大小

select OWNER “用户名”, t.segment_name “表名”, t.segment_type “表类型”, sum(t.bytes / 1024 / 1024) “表大小M”
from dba_segments t
where t.owner = ‘NC1221’
and t.segment_type=‘TABLE’
group by OWNER, t.segment_name, t.segment_type
order by “表大小M” desc;

查询出的结果：用户名 表名 表类型 表大小M