Is there a simpler way to achieve this style of user messaging?

Question

I have created a messaging system for users, it allows them to send a message to another user. If it is the first time they have spoken then a new conversation is initiated,

Answer 1

I haven't tested this approach as I don't have access to mysqldb right now. But, I think you should be able to get this done by using a ranking function. Since mysql doesn't have an equivalent of row_number function of Oracle I think you can do it like this:

Select * from (
Select 
    uc.id, 
    uc.user_id, 
    uc.friend_id 
    um.message
    um.read, 
    um.time,
    @rownum := IF(@prev_val = um.conversation_id, @rownum + 1, 1) AS rank,
    @prev_val := um.conversation_id
From
    userconversation uc,
    usermessages um,
    (select @row_num:=1) rows,
    (select @prev_val:='') partitions
Where 
    uc.id=um.conversation_id        
    and c.userId = 222 OR c.friendId = 222 

Order By 
    um.conversation_id,um.id desc
)t where t.rank=1