Summerize Time in area - sql

Question

i just have huge data of technitions that can be OnSite or OnTheWay ,
i want to summerize in witch site they been and for how long.
Example:
id UpdateTime UserName SiteID
488565 2019-02-18 19:07:24.000 stephen null
488388 2019-02-18 17:34:52.000 stephen 297
488558 2019-02-18 18:06:48.000 stephen 297
488565 2019-02-18 18:07:24.000 stephen 297
488565 2019-02-18 14:07:24.000 stephen null
483170 2019-02-18 13:53:14.000 stephen 299
488565 2019-02-18 11:07:24.000 stephen null
483170 2019-02-18 10:53:14.000 stephen 297
the technition was in 297 twice this day , i want to get this result per tech (End Time is the when i got Null or Diffrent SiteID):
UserName InComeTime TimeInSite(min) SiteID
stephen 2019-02-18 10:53:14.000 14 297
stephen 2019-02-18 13:53:14.000 14 299
stephen 2019-02-18 17:34:52.000 153 297
thanks,
eyal

Answer 1

Can't comment because no reputation :( ?!? so I'll post as answer although some questions remain. In principle you can work along the lines of joining null-value site records onto not-null site records. If you can't warrant that null-value siteIds mean 'exit' and not-null siteIds mean entry then there is no 'starting point' and you'd need to do a table scan. If you can warrant it (or deal with exceptions separately) then the query could take on the following form:
select t1.UserName,
t1.UpdateTime as EntryTime,
t2.UpdateTime as ExitTime,
datediff(MI, t1.UpdateTime, t2.UpdateTime) as TimeInSite,
t1.SiteId
from TimeTable t1
join TimeTable t2 on t2.id in
(select id from TimeTable
where
-- want the same user
UserName = t1.UserName
-- site id null/different means 'exited site'
and (siteId is null)
-- now get the entry with the minium update time that is greater than the entry time
and UpdateTime = (select min(UpdateTime) from TimeTable where UpdateTime > t1.UpdateTime
)
)
where t1.SiteId is not null
order by EntryTime
This does not take into account that you can have multiple 'not-null' siteIds for the same visit (i.e. the three 297s). Ideally this should be avoided. If you can't then you could first collate those entries into a temp table to only pick the the first entry time.
The above query outputs the following (SQL server, note that I have added entry and exit time for clarity). It is not 100% what you wanted because of the multiple 297s, but maybe it gets you started. Out of time now, maybe someone else can provide a 100% solution. Good luck!
UserName EntryTime ExitTime TimeInSite SiteId
------------ ----------------------- ----------------------- ----------- -----------
stephen 2019-02-18 10:53:14.000 2019-02-18 11:07:24.000 14 297
stephen 2019-02-18 13:53:14.000 2019-02-18 14:07:24.000 14 299
stephen 2019-02-18 18:07:24.000 2019-02-18 19:07:24.000 60 297

Answer 2

You can do this with window functions. You want to assign groups to the rows and then aggregate. How is the grouping defined?
In this case, you want to include the next NULL value in the group. So, a definition that works for you is the number of NULL values accumulated in reverse order. That is:
select t.*,
sum(case when siteId is null then 1 else 0 end) over (partition by userName order by updatetime desc) as grp
from t;
Then you can aggregate to get what you want:
select username, min(siteid) as siteid,
min(updatetime) as incometime,
datediff(minute, min(updatetime), max(updatetime)) as minutes
from (select t.*,
sum(case when siteId is null then 1 else 0 end) over (partition by userName order by updatetime desc) as grp
from t
) t;