MySQL - strange return for select clause

Question

Why does the following clause does not return, for each userId, it's last connection date ?
I have 31 distinct userids in the table, each one with many dates...

select userid, date from connections group by userid having date = max(date)

Answer 1

Why are you adding the having qualifier? If you want max date for each user's last connection try this:

select userid, max(date) from connections group by userid;