关于获取SQL数据问题

select  example_a from example where time <=2009-11-01 and time >= 2009-01-01
在这个SQL语句里能否直接得到第一行example_a数据和最后一行example_a数据呢？
我现在的解决方案是TOP 1，然后在倒序TOP 1，这样的话影响效率。

---

加个自增列
用max(id)和min(id)呢？

---

只能这样吧.

解决方案是TOP 1，然后在倒序TOP 1

---

SQL code:
select example_a
from example t
where [time] <='2009-11-01' and [time] >= '2009-01-01'
and
(not exists(select 1 from example where [time] <='2009-11-01' and [time] >= '2009-01-01' and [time]>t.[time])
or
not exists(select 1 from example where [time] <='2009-11-01' and [time] >= '2009-01-01' and [time]<t.[time])
)

---

在time上建索引

---

引用

SQL codeselect  example_afrom example twhere[time] <='2009-11-01'and[time]>='2009-01-01'and
(notexists(select1from examplewhere[time] <='2009-11-01'and[time]>='2009-01-01'and[time]>t.[time])ornotexists?-

UP

---

引用

SQL codeselect  example_afrom example twhere[time] <='2009-11-01'and[time]>='2009-01-01'and
(notexists(select1from examplewhere[time] <='2009-11-01'and[time]>='2009-01-01'and[tim