• My attempt:

    create table test (Attribute1 char(1), attribute2 char(1), attribute3 char(1), thetimestamp datetime)

    insert into test(Attribute1, attribute2, attribute3, thetimestamp)

    select 'A', 'B', 'C', '2013-09-02 16:06:30' union all

    select 'A', 'B', 'C', '2013-09-02 16:06:35' union all

    select 'A', 'B', 'C', '2013-09-02 16:06:30' union all

    select 'A', 'B', 'X', '2013-09-02 16:06:30' union all

    select 'A', 'B', 'C', '2013-09-02 16:06:20' union all

    select 'A', 'B', 'Y', '2013-09-02 16:06:30' union all

    select 'A', 'B', 'C', '2013-09-02 16:10:00'

    select c.Attribute1, c.attribute2, c.attribute3, c.thetimestamp

    from test as a

    cross apply (select b.Attribute1, b.attribute2, b.attribute3, MIN(thetimestamp) as thetimestamp

    from test as b

    where a.Attribute1 = b.Attribute1

    and a.attribute2 = b.attribute2

    and a.attribute3 = b.attribute3

    and datediff(ss, b.thetimestamp, a.thetimestamp ) <= 60

    group by b.Attribute1, b.attribute2, b.attribute3) as c

    group by c.Attribute1, c.attribute2, c.attribute3, c.thetimestamp

    select * from test

    drop table test

    ---------------------------------------------------------

    It takes a minimal capacity for rational thought to see that the corporate 'free press' is a structurally irrational and biased, and extremely violent, system of elite propaganda.
    David Edwards - Media lens[/url]

    Society has varying and conflicting interests; what is called objectivity is the disguise of one of these interests - that of neutrality. But neutrality is a fiction in an unneutral world. There are victims, there are executioners, and there are bystanders... and the 'objectivity' of the bystander calls for inaction while other heads fall.
    Howard Zinn