Break out timestamps to another column

[bonvin]

I have a table that looks something like this: 

Which is a log of  users performing different categories of activites. Due to the nature of the system that produces this log, I do not have an end timestamp for these activities, it only records when an activity is started.  Does anyone have any ideas how I can break out the starting timestamp of the next activity to another column, so that the table looks something like this: 

The data is from an SQL database that I load into Qlik by query, so if there are any SQL wizards here with a neat trick to get this done right at the source, I'm all ears. Or if there's some Qlik trick that can append such a column to the table afterwards, that's just as fine by me. I really have no clue where to even start with this. 

[mfchmielowski]

Hi.

You can load data by query you have already, then sort result by user ASC, date desc, starttime desc and use previous(startTime) function to determine endTime of current action. 

[mfchmielowski]

Sample:
load * inline [
	date, user, activity, startTime
	2021-05-23, 1, 1, 12:00
	2021-05-23, 1, 2, 14:00
	2021-05-23, 1, 3, 17:00
	2021-05-23, 2, 1, 12:00
	2021-05-23, 2, 2, 18:00
];

NoConcatenate
Result:
load *
	, if(user=Previous(user)
		, Previous(startTime)
	) as endTime
Resident Sample
order by user asc, date desc, startTime desc;

drop table Sample;

This code will give a table looking like this:

Hope it helps.