SQL 分組后,獲取每組中的最大值對應的數據

 

select gr,num,dt,(select bys from test where gr=b.gr and dt=b.dt) bys
from 
(
	select gr,count(0) num,max(dt) dt from test group by gr
) b

//如果有重復項，可用如下語句(針對Mysql的limit,Oracle 可用 rownum<2)

select gr,num,dt,(select bys from test where gr=b.gr and dt=b.dt limit 1) bys
from 
(
	select gr,count(0) num,max(dt) dt from test group by gr
) b