sql server 2000中怎样按时间分组筛选数据
表格结构

现在想按每小时取出一个ReadNumber（取每小时最小的） 由于是软件自动生成的数据 ReadDate数据类型是varchar
求具体写法 用的是sel server 2000
[解决办法]

select * from tb as t 
where not exists(select 1 from tb where 
convert(varchar(13),ReadDate,120)=convert(varchar(13),ReadDate,120)
and ReadNumber<t.ReadNumber
)

select convert(decimal(18,12),
replace(min(convert(char(13),readdate,120)+convert(varchar(18),ReadNumber)),
min(convert(char(13),readdate,120)),
'')
)
from tab
group by convert(char(13),readdate,120)

select convert(varchar(10),ReadyDate,120) 日期,datepart(hh,ReadyDate) 小时,min(ReadNumber) ReadNumber from [表]
group by convert(varchar(10),ReadyDate,120),datepart(hh,ReadyDate)