我想加入Rh,tam到如:
select Rh,tam,id,datatime=max(datatime) from datatable where id like 'T2%' group by id
为什么Rh和tam不包含在聚合函数group by里?
该怎么加?谢谢
select Rh,tam,id,datatime=max(datatime) from datatable where id like 'T2%' group by id
为什么Rh和tam不包含在聚合函数group by里?
该怎么加?谢谢
select Rh,tam,id,datatime=max(datatime) from datatable where id like 'T2%' group by id,rh,tam
select a.Rh,a.tam,b.id,b.datatime from datatable a left join(
select id,datatime=max(datatime) from datatable where id like 'T2%' group by id
)b on a.id=b.id
where id like 'T2%' group by id,Rh,tam
order id
假期了还在学习,精神可嘉!
select Rh,tam,id,datatime=max(datatime)
from datatable
where id like 'T2%'
group by id,rh,tam