求解一个求平均值的问题,先谢谢大家了
AA                     CC                     DD             EE
0002 USER0 12.0           0.0
5260 USER2 10.0           0.0
5260 USER2 10.0           0.0
0002 USER1 12.0           0.0
0002 USER1 12.0           0.0
5260 USER3 10.0           0.0
5260 USER4 10.0           0.0
5260 USER4 10.0           0.0
最后得到的结果如下:
AA                     CC                     DD             EE
0002 USER0 12.0           4
5260 USER2 10.0           2
5260 USER2 10.0           2
0002 USER1 12.0           4
0002 USER1 12.0           4
5260 USER3 10.0           2
5260 USER4 10.0           2
5260 USER4 10.0           2
即:根据AA的值做为分组的条件,   对DD的值进行平均得出EE的值
在ACCESS中以及在SQLSERVER中如何实现,谢谢

------解决方案--------------------
create table t(AA varchar(10),CC varchar(10),DD int)
insert t
select '0002 ', 'USER0 ',12
union all
select '5260 ', 'USER2 ',10
union all
select '5260 ', 'USER2 ',10
union all
select '0002 ', 'USER1 ',12
union all
select '0002 ', 'USER1 ',12
union all
select '5260 ', 'USER3 ',10
union all
select '5260 ', 'USER4 ',10
union all
select '5260 ', 'USER4 ',10

select a.aa,a.cc,a.dd,(select dd/count(dd) from t where dd = a.dd group by dd) ee from t a
------解决方案--------------------
create table T(AA varchar(10), CC varchar(10), DD decimal(10,1), EE decimal(10,1))
insert T select '0002 ', 'USER0 ', 12.0, 0.0
union all select '5260 ', 'USER2 ', 10.0, 0.0
union all select '5260 ', 'USER2 ', 10.0, 0.0
union all select '0002 ', 'USER1 ', 12.0, 0.0
union all select '0002 ', 'USER1 ', 12.0, 0.0
union all select '5260 ', 'USER3 ', 10.0, 0.0
union all select '5260 ', 'USER4 ', 10.0, 0.0
union all select '5260 ', 'USER4 ', 10.0, 0.0

select AA, CC, DD,
EE=cast(DD as int)/(select count(*) from T where AA=tmp.AA)
from T as tmp

--result
AA CC DD EE
---------- ---------- ------------ -----------
0002 USER0 12.0 4
5260 USER2 10.0 2
5260 USER2 10.0 2
0002 USER1 12.0 4
0002 USER1 12.0 4
5260 USER3 10.0 2
5260 USER4 10.0 2
5260 USER4 10.0 2

(8 row(s) affected)
------解决方案--------------------
create ta