求一复杂的条件排序语句

[fk424]

表中如下三个关键字段
sender,receiver,sendtime
数据如下:
11 21 2007-1-2
11 22 2007-1-3
21 11 2007-1-3
11 21 2007-1-4
22 11 2007-1-2
12 23 2007-1-2

排序后,希望结果如下:
11 21 2007-1-2
21 11 2007-1-3
11 21 2007-1-4

22 11 2007-1-2
11 22 2007-1-3

12 23 2007-1-2

万分感谢~

[gahade]

create table test_a(sender int,receiver int,sendtime datetime)
insert into test_a
select 11,21,'2007-1-2'
union all select 11,22,'2007-1-3'
union all select 21,11,'2007-1-3'
union all select 11,21,'2007-1-4'
union all select 22,11,'2007-1-2'
union all select 12,23,'2007-1-2'

select * from test_a
order by sender+receiver,sendtime

[wangdehao]

我晕，我看一大顿还没看出规律来呢

[fk424]

我的意思就是sender和receiver可能是互为发送和接收方的!我想先分组，再每组中再按照时间顺序排列!