查询指定日期最低出价问题
数据库设计:
ID                     int
Mobile             varchar
Price               money
JoinTime         Datetime

现需要查出指定日期无重复的最低出价的记录ID.   请高手帮忙解决下.   谢谢!

------解决方案--------------------
select mobile,min(price) as price,jointime from(select * from tablename group bymobile,price,jointime having count(*)=1)a group by mobile,jointime where convert(char(10),jointime,120)= '2007-09-14 '
------解决方案--------------------
/*测试*/
create table Ndata(
ID int,
Mobile varchar(100),
Price money,
JoinTime Datetime
)

insert into Ndata select 1, '0001 ',321, '2007-1-1 '
union all select 2, '0002 ',3213, '2007-1-3 '
union all select 3, '0031 ',3213, '2007-1-3 '
union all select 4, '0031 ',3213, '2007-9-14 '


/*语句*/
select JoinTime,
'价格 '=min(Price)
from Ndata
where datediff(dd,JoinTime,getdate())=0
group by JoinTime
having count(JoinTime)=1

/*结果*/
2007-09-14 00:00:00.000 3213.0000

------解决方案--------------------
declare @a table(Mobile varchar,Price money,JoinTime Datetime)
insert @a
select 'a ',100, '2007-08-01 '
union
select 'a ',10, '2007-08-01 '
union
select 'b ',100, '2007-08-01 '
union
select 'b ',10, '2007-08-01 '
union
select 'a ',10, '2007-08-02 '
union
select 'b ',10, '2007-08-02 '
select mobile,min(price) from @a where jointime= '2007-08-01 ' group by mobile

/*

（所影响的行数为 6 行）

mobile
------ ---------------------
a 10.0000
b 10.0000

（所影响的行数为 2 行）
*/