ORACLE 查看用户下表占用空间大小

方式一：

select  *　from user_segments s  where s.BYTES  is not null  order by s.BYTES desc 

方式二：

select segment_name,ROUND(sum(bytes) / (1024 * 1024 * 1024),2) as "size(G)" from user_segments group by segment_name order by sum(bytes) desc;