SQL: Find Continuous Date Ranges Across Multiple Rows?

I'm trying to get a start and end date combination for continuous spans of time worked. The spans can cross multiple rows, where the end date of the first row is the same as the en

Solution 1:

Sample data

create table tbl (person int, startdate datetime, enddate datetime, hours decimal(10,2));
insert tbl values
(5163 ,'2013-04-29 07:00:00.000' ,'2013-04-29 11:00:00.000', 4.00),
(5163 ,'2013-04-29 11:30:00.000' ,'2013-04-29 15:30:00.000', 4.00),
(5163 ,'2013-04-29 15:30:00.000' ,'2013-04-29 19:06:00.000', 3.60),
(5851 ,'2013-05-02 19:00:00.000' ,'2013-05-02 23:00:00.000', 4.00),
(5851 ,'2013-05-02 23:00:00.000' ,'2013-05-03 00:00:00.000', 1.00),
(5851 ,'2013-05-03 00:00:00.000' ,'2013-05-03 00:31:00.000', 0.52);

The query

;with cte as (
    select person, startdate, enddate, hours
    from tbl
    union all
    select t.person, cte.startdate, t.enddate, cast(cte.hours + t.hours as decimal(10,2))
    from cte
    join tbl t on cte.person = t.person and cte.enddate = t.startdate
), cte2 as (
    select *, rn = row_number() over (partition by person, enddate order by startdate)
    from cte
)
select person, startdate, max(enddate) enddate, max(hours) hours
from cte2
where rn=1
group by person, startdate
order by person, startdate;

Results

person      startdate               enddate                 hours
----------- ----------------------- ----------------------- -------
5163        2013-04-29 07:00:00.000 2013-04-29 11:00:00.000 4.00
5163        2013-04-29 11:30:00.000 2013-04-29 19:06:00.000 7.60
5851        2013-05-02 19:00:00.000 2013-05-03 00:31:00.000 5.52