如何提高分组查询效率
本人新手最近被oracle查询优化搞的焦头烂额,希望有大神能给点意见
查询如下:
select r.deptcode,
r.combno,
count(distinct r.phyno) as rs
from r,
s
where (r.phyno = s.phyno)and
(r.deptcode = s.deptcode)and
(r.checkdate >= to_date('2016/1/1','yyyy/mm/dd'))and
(r.checkdate <= to_date('2016/11/1','yyyy/mm/dd'))and
(s.endflag = '1')
group by r.deptcode,r.combno
因为数据量很大,分组查询至少要半分钟