Calculate interval time using SQL - sql

Question

I need to calculate the call waiting time (Hold time) during an interval of 30 minutes
HoldTime is given in seconds
Input Data
| Date | ID |StartDate | StartTime |holdtime |
--------- ------- ---------- -------------------- ---------
28/12/2022 3110522 28/12/2022 10:03:46.0000000 62
28/12/2022 3110522 28/12/2022 10:36:42.0000000 189
28/12/2022 3110522 28/12/2022 11:06:54.0000000 65
28/12/2022 3110522 28/12/2022 11:11:46.0000000 79
28/12/2022 3110522 28/12/2022 11:19:55.0000000 118
28/12/2022 3110522 28/12/2022 11:38:20.0000000 36
28/12/2022 3110522 28/12/2022 12:13:46.0000000 67
28/12/2022 3110522 28/12/2022 13:45:27.0000000 24
28/12/2022 3110522 28/12/2022 13:52:59.0000000 144
28/12/2022 3110522 28/12/2022 15:02:43.0000000 39
28/12/2022 3110522 28/12/2022 16:00:41.0000000 246
28/12/2022 3110522 28/12/2022 16:54:22.0000000 79
28/12/2022 3110522 28/12/2022 16:59:18.0000000 94
28/12/2022 3110522 28/12/2022 17:29:19.0000000 84
28/12/2022 3110522 28/12/2022 17:54:44.0000000 64
Output Data
|ID | StartDate |intervalStartTime | intervalStoptTime | holdtime
------ --------- ----------------- ------------------- ----------
3110522 28/12/2022 10:00:00.000 10:30:00.0000000 62
3110522 28/12/2022 10:30:00.000 11:00:00.0000000 189
3110522 28/12/2022 11:00:00.000 11:30:00.0000000 262
3110522 28/12/2022 11:30:00.000 12:00:00.0000000 36
3110522 28/12/2022 12:00:00.000 12:30:00.0000000 67
3110522 28/12/2022 13:30:00.000 14:00:00.0000000 168
3110522 28/12/2022 15:00:00.000 15:30:00.0000000 39
3110522 28/12/2022 16:00:00.000 16:30:00.0000000 246
3110522 28/12/2022 16:30:00.000 17:00:00.0000000 121
3110522 28/12/2022 17:00:00.000 17:30:00.0000000 93
3110522 28/12/2022 17:30:00.000 18:00:00.0000000 107
I am making a function to split data, however I am not getting what I want. I think I'm doing something too complicated to solve it. Using a loop like WHILE is not something I like to use in SQL.
while (#eventDurationMins>0)
begin
set #eventDurationInIntervalMins = cast(#intervalEndTime-#eventStartTime as float)*24*60 ;
if #eventDurationMins<#eventDurationInIntervalMins
set #eventDurationInIntervalMins = #eventDurationMins ;
insert into #retTable
select #intervalStartTime,#intervalEndTime,#eventDurationInIntervalMins
set #eventDurationMins = #eventDurationMins - #eventDurationInIntervalMins ;
set #eventStartTime = #intervalEndTime;
set #intervalStartTime = #intervalEndTime;
set #intervalEndTime = dateadd(minute,#intervalMins,#intervalEndTime);
end;
Thanks in advance,

Answer 1

They key here is to find the timeslot in 30 minutes. The TimeSlot computation is basically to "round down" the time to every 30 minutes. Example : from 10:00 to 10:29 round down to 10:00 etc
select ID, StartDate,
intervalStartTime = TimeSlot,
intervalStoptTime = dateadd(minute, 30, TimeSlot),
holdtime = sum(holdtime)
from
(
select *,
TimeSlot = convert(time(0),
dateadd(second,
convert(int,
datediff(second, '00:00:00', StartTime)
/ 30.0 / 60.0) * 30 * 60, '00:00'))
from InputData
) i
group by ID, StartDate, TimeSlot
Edit :
CTE numbers is just a tally table. It is used to explode those rows where the holdTime span across multiple time slot
The holdtime (ht) is calculated in below case expression. First condition is where the hold time contains within same time slot. The remaining 3 conditions are to handle when the explode case
ht = case when n = 0
and count(*) over(partition by [Date], [ID], [StartDate], [StartTime]) = 1
then holdTime
when n = 0
then datediff(second, StartTime, dateadd(minute, 30, TimeSlot))
when n = count(*) over(partition by [Date], [ID], [StartDate], [StartTime]) - 1
then datediff(second, dateadd(minute, n * 30, TimeSlot), EndTime)
else 30 * 60
end
The query
with
numbers as
(
select n = 0
union all
select n = n + 1
from numbers
where n < 99
),
cte as
(
select *
from InputData i
cross apply
(
select EndTime = dateadd(second, holdTime, StartTime),
TimeSlot = convert(time(0),
dateadd(second,
convert(int,
datediff(second, '00:00:00', StartTime)
/ 30.0 / 60.0) * 30 * 60, '00:00'))
) t
cross apply
(
select EndTimeSlot = convert(time(0),
dateadd(second,
convert(int,
datediff(second, '00:00:00', EndTime)
/ 30.0 / 60.0) * 30 * 60, '00:00'))
) e
),
cte2 as
(
select [Date], [ID], [StartDate], [StartTime], [EndTime],
TimeSlot = dateadd(minute, n * 30, TimeSlot),
ht = case when n = 0
and count(*) over(partition by [Date], [ID], [StartDate], [StartTime]) = 1
then holdTime
when n = 0
then datediff(second, StartTime, dateadd(minute, 30, TimeSlot))
when n = count(*) over(partition by [Date], [ID], [StartDate], [StartTime]) - 1
then datediff(second, dateadd(minute, n * 30, TimeSlot), EndTime)
else 30 * 60
end
from cte i
inner join numbers n
on n.n >= 0
and n.n <= datediff(minute, TimeSlot, EndTimeSlot) / 30
)
select ID, StartDate,
intervalStartTime = TimeSlot,
intervalStoptTime = dateadd(minute, 30, TimeSlot),
holdtime = sum(ht)
from cte2
group by ID, StartDate, TimeSlot
order by intervalStartTime
db<>fiddle demo