疑难SQL语句问题！请教！

[feiyafei2008]

'发贴统计
select poster as 用户名,count(*) as 发贴次数,sum(len(message)) as 发贴字数 From dnt_posts1 where fid = 7 and layer = 0 and postdatetime >= #02/01/2010# group by poster

'回贴统计
select poster as 用户名,count(*) as 回贴次数,sum(len(message)) as 回贴字数 From dnt_posts1 where fid = 7 and layer = 1 and postdatetime >= #02/01/2010# group by poster

怎么能将其合并成一条： “用户名，发贴次数，发贴字数，回贴次数，回贴字数”。

数据库是ACCESS。

[htl258_Tony]

select poster as 用户名,
	sum(iif(layer = 0,1,0) as 发贴次数,
	sum(iif(layer = 1,1,0) as 回贴次数
	sum(len(message)) as 回贴字数 
from dnt_posts1 
where fid = 7 and postdatetime >= #02/01/2010# 
group by poster 

[ACMAIN_CHM]

select poster as 用户名,
	sum(iif(layer = 0,1,0)) as 发贴次数,sum(iif(layer = 0,len(message),0)) as 发贴字数 
	sum(iif(layer = 1,1,0)) as 回贴次数,sum(iif(layer = 1,len(message),0)) as 回贴字数 
From dnt_posts1 where fid = 7 
and postdatetime >= #02/01/2010# 
group by poster

[-狙击手-]

select poster as 用户名,
sum(case layer = 0 then 1 else 0 end) as 回贴次数,
sum(case layer = 1 then 1 else 0 end) as 回贴次数
sum(len(message)) as 回贴字数 
From dnt_posts1 
where fid = 7 and postdatetime >= #02/01/2010# 
group by poster 

[-狙击手-]

sum(case when layer = 0 then 1 else 0 end) as 回贴次数,
sum(case when layer = 1 then 1 else 0 end) as 回贴次数


access 改用iff判断