SQL Server 2017

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create table Safety_SIMS (
CompLast_SignON_datetime smalldatetime, 
comp_accidentdate_time smalldatetime
)
insert into Safety_SIMS 
(CompLast_SignON_datetime, comp_accidentdate_time) values
  ('2021-12-16 04:08', '2021-12-16 05:10')
, ('2021-12-17 14:20', '2021-12-17 20:00')
, ('2021-12-18 12:15', '2021-12-18 15:25') 
, ('2021-12-22 06:00', '2021-12-22 12:34') 
, ('2021-12-25 11:30', '2021-12-25 21:40') 
, ('2021-12-26 21:00', '2021-12-27 02:50') 
6 rows affected

select *
, [Duty_hours] = format(datediff(hour, CompLast_SignON_datetime, comp_accidentdate_time), '00')
                 + format(comp_accidentdate_time - CompLast_SignON_datetime, ':mm')
from Safety_SIMS;


CompLast_SignON_datetime
comp_accidentdate_time
Duty_hours


2021-12-16 04:08
2021-12-16 05:10
01:02

2021-12-17 14:20
2021-12-17 20:00
06:40

2021-12-18 12:15
2021-12-18 15:25
03:10

2021-12-22 06:00
2021-12-22 12:34
06:34

2021-12-25 11:30
2021-12-25 21:40
10:10

2021-12-26 21:00
2021-12-27 02:50
05:50


select *
, [Duty_hours] = format(comp_accidentdate_time - CompLast_SignON_datetime, 'HH:mm')
from Safety_SIMS;


CompLast_SignON_datetime
comp_accidentdate_time
Duty_hours


2021-12-16 04:08
2021-12-16 05:10
01:02

2021-12-17 14:20
2021-12-17 20:00
05:40

2021-12-18 12:15
2021-12-18 15:25
03:10

2021-12-22 06:00
2021-12-22 12:34
06:34

2021-12-25 11:30
2021-12-25 21:40
10:10

2021-12-26 21:00
2021-12-27 02:50
05:50


select *
, [Duty_hours] = datediff(hour, CompLast_SignON_datetime, comp_accidentdate_time)
                 + cast(format(comp_accidentdate_time - CompLast_SignON_datetime, '.mm') as decimal(10,2))
from Safety_SIMS;


CompLast_SignON_datetime
comp_accidentdate_time
Duty_hours


2021-12-16 04:08
2021-12-16 05:10
1.02

2021-12-17 14:20
2021-12-17 20:00
6.40

2021-12-18 12:15
2021-12-18 15:25
3.10

2021-12-22 06:00
2021-12-22 12:34
6.34

2021-12-25 11:30
2021-12-25 21:40
10.10

2021-12-26 21:00
2021-12-27 02:50
5.50

CompLast_SignON_datetime	comp_accidentdate_time	Duty_hours
2021-12-16 04:08	2021-12-16 05:10	01:02
2021-12-17 14:20	2021-12-17 20:00	06:40
2021-12-18 12:15	2021-12-18 15:25	03:10
2021-12-22 06:00	2021-12-22 12:34	06:34
2021-12-25 11:30	2021-12-25 21:40	10:10
2021-12-26 21:00	2021-12-27 02:50	05:50

CompLast_SignON_datetime	comp_accidentdate_time	Duty_hours
2021-12-16 04:08	2021-12-16 05:10	1.02
2021-12-17 14:20	2021-12-17 20:00	6.40
2021-12-18 12:15	2021-12-18 15:25	3.10
2021-12-22 06:00	2021-12-22 12:34	6.34
2021-12-25 11:30	2021-12-25 21:40	10.10
2021-12-26 21:00	2021-12-27 02:50	5.50