Query only latest entry for each user - sql

Question

The goal of the following query is, to check whether a user has been terminated in the system in time. So there is a table that contains information about the system termination (how and when the user has been terminated) and one with the termination date of the user. Since there are three ways to terminate a user, some users have several termination entries. In the end, I only want to see the latest entry before their termination date if they have been terminated at all. All Date fields are INT fields.
Current Query:
Select
B.TerminationApproach,
B.SystemTerminationDate,
A.UserName,
A.LastName,
A.FirstName,
A.TerminationDate,
Case
When B.SystemTerminationDate <= A.TerminationDate Then 0
Else 1
End As EvalCheck
From A
Left Join B On B.User = A.UserName
Current Result:
TerminationApproach SystemTerminationDate TerminationDate UserNAme LastName FirstName EvalCheck
No profiles 20180301 20180226 AWALL Wall Aaron 1
Locally locked 20181027 20180226 AWALL Wall Aaron 1
Deleted 20180301 20180226 AWALL Wall Aaron 1
No profiles 20180301 20180301 CBLAIR Blair Carlos 0
Locally locked 20181027 20180301 CBLAIR Blair Carlos 1
No profiles 20180301 20180301 CBLAIR Blair Carlos 0
Then there is a third table which contains user activity. I need to map the results of my first query to the user activity, to see whether the user has performed changes after in the system after his termination date. The third table looks like this:
UserID Date Activity
AWALL 20180227 Table Change
So with my example, the end result of my query should look like this:
TerminationApproach SystemTerminationDate TerminationDate UserNAme LastName FirstName EvalCheck ActivityAfterTermination
No profiles 20180301 20180226 AWALL Wall Aaron 1 Yes
No profiles 20180301 20180301 CBLAIR Blair Carlos 0 No

Answer 1

Your question and your query are rather disconnected. It is not clear what columns represent a user or the date you care about.
But the basic idea is:
with t as (
<your query here>
)
select t.*
from (select t.*,
row_number() over (partition by UserId order by date desc) as seqnum
from t
) t
where seqnum = 1;