Resumir a coluna Time usando a consulta sql

CREATE TABLE Table2
    ([repID] int, [ClockIn] datetime, [ClockOut] datetime, [TotalHours] varchar(7))
;

INSERT INTO Table2
    ([repID], [ClockIn], [ClockOut], [TotalHours])
VALUES
    (109145, '7:50:50 AM', '3:37:16 PM', '7:46:26'),
    (109145, '7:52:41 AM', '3:44:51 PM', '7:52:10'),
    (109145, '8:42:40 AM', '3:46:29 PM', '7:3:49'),
    (109145, '7:50:52 AM', '3:42:59 PM', '7:52:7'),
    (109145, '8:09:23 AM', '3:36:55 PM', '7:27:32')
;

SELECT convert(varchar(8), dateadd(second, SUM(DATEDIFF(SECOND, ClockIn, ClockOut)), 0),  108)
from Table2
group by repID

| COLUMN_0 |
------------
| 14:02:04 |

select sum(datediff(second,ClockIn,ClockOut))/3600 as hours_worked
from Table2

| hours_worked|
------------
|       38 |

select sum(datediff(minute, 0, TotalHours)) / 60.0 as hours_worked
from Table2

| HOURS_WORKED |
----------------
|           38 |