Lookup should work for you:
Lookup(attr(time),0) - Lookup(attr(time),-1)
Also make sure you in compute using you uncheck booking ID.
Find the attached workbook
1) Arrange your layout like below
2) Create a calculated field like below
3) Click on the calculated field --> Default Properties --> Number Format
4)Go to Custom and change the format to hh "hr" mm "min" ss "sec" like below
5) Convert the created calculated field to discrete
6) Drag the calculated field to Text
7) Click on the field added to text --> edit table calculation
8) Select the field like below
Hope this helps
Plz mark this answer as correct or helpful to close the thread
Example 011018_v10.2.twbx 26.6 KB
Exactly what I was looking for.
Appreciate the detailed explanation!