KQL remove from the output strings which have a duplicated value in one of the columns

Question

Let's say I have a table with records about users who had passed certain doors.

I want to remove from the output all strings with records about users that passed 1st door if there is a record about them passing the 2nd door.

summarise by distinct could not be used because I need to keep Timestamp.

PS In reality, the event registration time differs by thousandths of a second. That's I don't want to use only the later events. It seems to me more correct is to leave only the record with an event of the first type if there is an event of the second type.

Answer 1

datatable(Name:string,Source:string,Timestamp:timespan)
[
    'Jack', '1StDoor', '1:01'
   ,'Jill', '1StDoor', '1:02'
   ,'Jill', '2ndDoor', '1:03'
   ,'Mike', '1StDoor', '1:04'
   ,'John', '1StDoor', '1:05'
   ,'John', '2ndDoor', '1:06'
]
| summarize arg_max(Source, *) by Name

Name	Source	Timestamp
Jack	1StDoor	01:01:00
Jill	2ndDoor	01:03:00
Mike	1StDoor	01:04:00
John	2ndDoor	01:06:00

Fiddle