create table a(账号 varchar(10),日期 varchar(10),余额 int)
insert into a 
select '001','20110101',100
union all select 
'002','20110101',200
union all select 
'003','20110101',100
union all select 
'001','20110102',100
union all select 
'002','20110102',210
union all select 
'003','20110102',150
union all select 
'001','20110103',100
union all select 
'002','20110103',220
union all select 
'003','20110103',100
select * from a

select 账号
from a
where 日期 between '2011-01-01' and '2011-01-03'
group by 账号
having max(余额)=min(余额)

/*
001
*/

------解决方案--------------------
if OBJECT_ID('tbl')is not null
drop table tbl
go
create table tbl(
账号 varchar(10),
日期 varchar(10),
余额 int)
insert into tbl
select '001','20110101',100 union all  
select '002','20110101',200 union all 
select '003','20110101',100 union all  
select '001','20110102',100 union all  
select '002','20110102',210 union all  
select '003','20110102',150 union all  
select '001','20110103',100 union all  
select '002','20110103',220 union all  
select '003','20110103',100

select 账号 from tbl where 日期 between '20110101' and '20110103'
group by 账号
having MAX(余额)=MIN(余额)
/*
结果表
账号
001
*/