how to caluculate average of duration(starttime-endtime)

[to1234]

create table #ExamDur(DtTm datetime,startTm datetime,EndTm datetime,Duration int,duration1 varchar(20))
insert into #ExamDur(DtTm,startTm,EndTm,Duration,duration1)
select UE.CreatedDtTm,ED.StartTime,ED.EndTime,
datediff(mi,ed.starttime,ed.endtime) duration ,
cast(datediff(mi,ED.StartTime,ED.EndTime)as varchar(20))+':'+
cast(DATEPART(SECOND,(ed.EndTime-ed.StartTime) )as varchar(20)) Duration1 
 from UserExamMap UE left join  ExamDuration ED on UE.Id=ED.ExamId where UE.UserId=1--@UserID
 
 
select p.Sno SNo,p.dt Date,p.chapter Chapter,p.chpaterid ChapterID,p.userid UserID,p.topic Topic,p.marks Marks
,p.percentage Percentage,cast(datepart(HOUR,ED.Duration1) as varchar(10))+':'+cast(datepart(MINUTE,ed.duration1)as varchar(10)) ExamDuration1 from #ExamDur ED inner join #Practice p on p.dt=ED.DtTm order by p.Sno
 
select Duration AvgTmSpent from #ExamDur
 
end

[Rabbit]

Please use code tags when posting code.

To calculate the average duration, I would use DATEDIFF to get the number of seconds between the two date times and use an aggregate query to calculate the average.