数据库能够按照时间频率进行统计吗？

Question

A B C D Time
abraham         abraham         123456 654321 2010-6-26 5:11
abraham         abuse           123456 654321 2010-6-26 5:11
abraham         access          123456 654321 2010-6-26 5:11
abraham         account         123456 654321 2010-6-26 5:11
abraham         accounts        123456 654321 2010-6-26 5:11
abraham         adam            123456 654321 2010-6-26 5:11
abraham         adm             123456 654321 2010-6-26 5:11
abraham         admin2          123456 654321 2010-6-26 5:11
abraham         admin           123456 654321 2010-6-26 5:11
abraham         adrian          123456 654321 2010-6-26 5:11
aerial          aerial          123456 654321 2010-6-26 5:11
agent           agent           123456 654321 2010-6-26 5:12
alan            alan            123456 654321 2010-6-26 5:12
abraham         albert          123456 654321 2010-6-26 5:12
alberto         alberto         123456 654321 2010-6-26 5:12
abraham         alfonso         123456 654321 2010-6-26 5:13
alfred          alfred          123456 654321 2010-6-26 5:13
alice           alice           123456 654321 2010-6-26 5:13
alicia          alicia          123456 654321 2010-6-26 5:13
alison          alison          123456 654321 2010-6-26 5:13
allen           allen           123456 654321 2010-6-26 5:14
allie           allie           123456 654321 2010-6-26 5:14
allie           alpha           123456 654321 2010-6-26 5:14
allie           alvin           123456 654321 2010-6-26 5:14
allie           amelia          123456 654321 2010-6-26 5:14
allie           alyssa          123456 654321 2010-6-26 5:14
allie           amanda          123456 654321 2010-6-26 5:14
andre           andre           223457 654321 2010-6-26 5:15
anderson        anderson        223458 654321 2010-6-26 5:15
andreea         andreea         223459 654321 2010-6-26 5:15如上段数据，在很短的两分钟内，很多字段的A相同，B不同，我想挑出这些数据，谢谢。
规则可以按照： 两分钟内出现了对于相同的A，出现5个以上的不同B的所有数据。
谢谢。

Answer 1

select * 
from tablename
where (a,b) in
(select a,b
from tablename
group by a,b
having count(*)>5
)

Answer 2

这句只能找出 对于相同的A，出现5个以上的B值的数据。 不能体现5个以上不同B值的数据

Answer 3

1:测试数据:
select * from tb11;
A B TIME C D
abraham abraham 2010-06-26 05:11:00 654321 123456
abraham abuse 2010-06-26 05:11:00 654321 123456
abraham access 2010-06-26 05:11:00 654321 123456
abraham account 2010-06-26 05:11:00 654321 123456
abraham account 2010-06-26 05:11:00 654321 123456
abraham adm 2010-06-26 05:11:00 654321 123456
abraham adm 2010-06-26 05:11:00 654321 123456
abraham admin 2010-06-26 05:11:00 654321 123456
abraham admin 2010-06-26 05:11:00 654321 123456
abraham adrian 2010-06-26 05:11:00 654321 123456
aerial aerial 2010-06-26 05:11:00 654321 123456
agent agent 2010-06-26 05:12:00 654321 123456
alan alan 2010-06-26 05:12:00 654321 123456
abraham albert  2010-06-26 05:12:00 123456 123456
alberto alberto 2010-06-26 05:12:00 123456 123456
abraham albert 2010-06-26 05:12:00 654321 123456
alberto alberto 2010-06-26 05:12:00 654321 123456
abraham alfonso 2010-06-26 05:13:00 654321 123456select ta.* from 
(select a,b,c,d,time,decode(mod((time-bs)*24*60,2),0,(time-bs)*24*60/2+1,floor((time-bs)*24*60/2+1)) as cnt
            from tb11,(select min(time) as bs from tb11) t) ta
where (ta.a,ta.cnt) in (
    --求出2分钟内A同,B不同并且B有5种以上的记录,
    select a,cnt from 
    (    --求出2分钟内不重复记录
        select distinct a,b,cnt
        from(
        --所有记录按2分钟进行分组
            select a,b,time,decode(mod((time-bs)*24*60,2),0,(time-bs)*24*60/2+1,floor((time-bs)*24*60/2+1)) as cnt
            from tb11,(select min(time) as bs from tb11) t
         )
    )
    group by a,cnt
    having count(b)>5
)结果:
A B C D TIME CNT
abraham abraham 654321 123456 2010-06-26 05:11:00 1
abraham abuse 654321 123456 2010-06-26 05:11:00 1
abraham access 654321 123456 2010-06-26 05:11:00 1
abraham account 654321 123456 2010-06-26 05:11:00 1
abraham account 654321 123456 2010-06-26 05:11:00 1
abraham adm 654321 123456 2010-06-26 05:11:00 1
abraham adm 654321 123456 2010-06-26 05:11:00 1
abraham albert  123456 123456 2010-06-26 05:12:00 1
abraham albert 654321 123456 2010-06-26 05:12:00 1
abraham admin 654321 123456 2010-06-26 05:11:00 1
abraham admin 654321 123456 2010-06-26 05:11:00 1
abraham adrian 654321 123456 2010-06-26 05:11:00 1
allie allie 654321 123456 2010-06-26 05:14:00 2
allie alpha 654321 123456 2010-06-26 05:14:00 2
allie alvin 654321 123456 2010-06-26 05:14:00 2
allie amelia 654321 123456 2010-06-26 05:14:00 2
allie alyssa 654321 123456 2010-06-26 05:14:00 2
allie amanda 654321 123456 2010-06-26 05:14:00 2