求教子查询的写法?

假设以下子查询得到的表结构如下:

select * from 
(
.......
.......
.......
) a

thedate price
2011-01-04 32
2011-01-05 3
2011-01-06 8


在这个基础上,我想求得,每一个日期之前所有日期的price总和,在上面的子查询基础上应该再怎么写?

希望结果是:

thedate price total
2011-01-04 32 32
2011-01-05 3 35
2011-01-06 8 43

SQL code

select *,(select sum(price) from tb where thedate<=a.thedate ) from  
(
.......
.......
.......
)

SQL code

select *,(select sum(price) from tb where thedate<=a.thedate ) from  
(
.......
.......
.......
)a
--忘了一个a