group by rollup() 按分组合计
select grouping(status),status,owner,object_type,count(*) from dba_objects
where owner not in (‘SYS‘,‘SYSTEM‘)
group by rollup (status,owner,object_type)
order by status,owner,object_type;
经典分类查询语句：
select object_type,count(*) from
( select decode(object_type,‘TABLE‘,‘TABLE‘,‘INDEX‘,‘INDEX‘,‘OTHERS‘) object_type from dba_objects )
group by rollup(object_type);