Using ORDER BY and GROUP BY together

Question

My table looks like this (and I\'m using MySQL):

m_id | v_id | timestamp
------------------------
6    |   1  | 1333635317
34   |   1  | 1333635323
34   |            


        

Answer 1

If you really don't care about which timestamp you'll get and your v_id is always the same for a given m_i you can do the following:

select m_id, v_id, max(timestamp) from table
group by m_id, v_id
order by timestamp desc

Now, if the v_id changes for a given m_id then you should do the following

select t1.* from table t1
left join table t2 on t1.m_id = t2.m_id and t1.timestamp < t2.timestamp
where t2.timestamp is null
order by t1.timestamp desc