/*

测试数据：

Create Table tbl([日期] smalldatetime,[收入] int ,[支出] int) 

Insert Into tbl

SELECT '2004-02-11', 60, 45

union SELECT '2004-10-01',60, 45

union SELECT '2004-10-02',40, 50

union SELECT '2004-10-15',50, 40

union SELECT '2004-10-16',10, null

union SELECT '2004-10-19',10, 0

union SELECT '2004-10-30',0, 10

*/ 

--select *,(select sum(收入-支出) from 表 where 你的表的主键<=tem.你的表的主键) 本次余额 from 表 tem 

select t.日期,t.收入,t.支出,(select sum(ISNULL(收入, ))-sum(ISNULL(支出, )) from tbl where 日期 <= t.日期) as 本期余额

from tbl t order by 日期 desc