Update the column value from a previous row

[Paulo_IntelFab]

Hi, guys. 
 I need to set the downtime value of a machine according to the time where the machine stop occurred. 
 My table is something like this:

Shift	Interval	Interval	Downtime
1	12	07:34:34	0
2	1234	14:12:12	398

In this case, I need to split the downtime between Shifts 1 and 2 (because most of time stopped was on Shift 1). 
The expected values are something like this:

Shift	Interval	Interval	Downtime
1	12	07:34:34	386
2	1234	14:12:12	12

How can I, detecting this change of Shift (using Previous(Shift), update the last row of the Shift 1? 
I appreciate any help. 

[pedrobergo]

Hey @Paulo_IntelFab 

Which product you´re referring to?

This forum is for Qlik Cloud Data Integration.

[],

Pedro

[Paulo_IntelFab]

Hi @pedrobergo . Thanks for replying. 
I'll try on another forum.