References previous value based on user ID

[hoppalong]

I have the following sample data which has been pulled from application logs. 

The login/logout events have a corresponding UserID & Username. When the application disconnects the user it only provides the Usernum and not their actual username making it difficult to identify who has been repeatedly disconnected. 

I've joined my login/logout/disconnected events into one table and would like to somehow replace those null values within the AD_User by referencing the previous usernum id.

[Anonymous]

Hi @hoppalong ,

I tested Omid_Motamedise's reply and it works well!
If Omid_Motamedise's reply helps you, please remember to accept the reply as solution to help the other members find it more quickly. Thank you!

Best Regards,
Dino Tao

[Omid_Motamedise · Accepted solution]

use this code

= Table.Group(Source, {"Username"}, {{"Count", each Table.FillDown(_,{"AD_User"})}})