Question

I have an activity log table on a site. There are columns for date/time, userID and IP address for each log-in.

I want to retrieve a list of unique usernames and the most recent IP address they logged in from.

What’s the best way to retrieve this from the table using t-sql on SQL Server?

Answer 1

A portable approach is:

select l.userID, l.Date, l.IpAddress
from (
    select userID, max(Date) as MaxDate
    from Log
    group by userID
) lm
inner join Log l on lm.userID = l.userID
    and lm.MaxDate = l.Date

If you have SQL Server 2005+, you can also do:

select * from
(
    select userID, Date, IpAddress,  
        Rank() over (Partition BY userID order by Date DESC) as Rank
    from Log
) tmp
where Rank = 1