CODEWITHSUNDEEP
phpmysqllaravel
Guy Mazouz
Guy Mazouz

Reputation: 437

Messages table in MySQL, getting last message for each thread

I am trying to get the last message from each conversation, the only problem is I am not using a conversations table.

I am using one messages table, my table columns looks like this:

id  from_id     to_id   text    isread  isseen  created_at  updated_at

Right now I am able to retrieve conversations like this:

$messages = Message::select('*')->
                from(DB::raw("(select * from `messages` where `to_id` = ".Auth::id()." order by `created_at` desc) as sub"))->
                groupBy('from_id')->orderBy('created_at', 'desc')->
                paginate(7);

The only downside to this is I am not retrieving the last message for each conversation, I am retrieving the last message received.

How can I retrieve the last message of each conversation?

Example Retrieve user63 conversations and last message for each conversation:

id  from_id     to_id   text    isread  isseen  created_at  updated_at 
23  224         63      a        0         0    2015-03-28 22:23:54     2015-03-28 22:23:54
20  63          225     b        0        0     2015-03-28 22:23:06     2015-03-28 22:23:06
16  225         63      hi       0        1     2015-03-28 22:21:32     2015-03-28 22:21:32

I thought of an idea, not sure though:

$messages = Message::select('*')->
            from(DB::raw("
(
(select *, to_id as theuser from `messages` where `to_id` = ".Auth::id()." order by `created_at` desc)
union
(select *, from_id as theuser from `messages` where `from_id` = ".Auth::id()." order by `created_at` desc) group by theuser
) as sub"))->
            groupBy('from_id')->orderBy('created_at', 'desc')->
            paginate(7);

Upvotes: 2

Views: 940

Answers (2)

Guy Mazouz
Guy Mazouz

Reputation: 437

I found a solution myself, thanks everyone! :)

$messages = Message::select('*')->
from(DB::raw("
    ( 
      SELECT *,`from_id` as `theuser`
      FROM `messages` WHERE `to_id` = 63
      union
      SELECT *,`to_id` as `theuser`
      FROM `messages` WHERE `from_id` = 63
      order by `created_at` desc
    ) as `sub`"))->groupBy('theuser')->
                   orderBy('created_at', 'desc')->
                   paginate(7);

Upvotes: 2

Edgar Orozco
Edgar Orozco

Reputation: 2782

This must works too: The difference in this approach is a self join with a little help from max() function like this:

SELECT from_id, MAX(created_at) AS last FROM messages GROUP BY from_id

So:

$pagedMessages = Message::select('*')->
  from(
    DB::raw("
        messages AS m 
        JOIN (
            SELECT from_id, MAX(created_at) AS lm FROM messages GROUP BY from_id
        ) AS lm 
        ON lm.from_id = m.from_id AND lm.created_at = m.created_at 
    "))->
paginate(7);

Upvotes: 2

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